Provided by: fio_3.35-2_amd64 bug

NAME

       fio - flexible I/O tester

SYNOPSIS

       fio [options] [jobfile]...

DESCRIPTION

       fio  is a tool that will spawn a number of threads or processes doing a particular type of
       I/O action as specified by the user.  The typical use of  fio  is  to  write  a  job  file
       matching the I/O load one wants to simulate.

OPTIONS

       --debug=type
              Enable  verbose  tracing type of various fio actions. May be `all' for all types or
              individual types separated by a comma (e.g. `--debug=file,mem' will enable file and
              memory debugging). `help' will list all available tracing options.

       --parse-only
              Parse options only, don't start any I/O.

       --merge-blktrace-only
              Merge blktraces only, don't start any I/O.

       --output=filename
              Write output to filename.

       --output-format=format
              Set the reporting format to `normal', `terse', `json', or `json+'. Multiple formats
              can be selected, separate by a comma. `terse' is a CSV  based  format.  `json+'  is
              like `json', except it adds a full dump of the latency buckets.

       --bandwidth-log
              Generate aggregate bandwidth logs.

       --minimal
              Print statistics in a terse, semicolon-delimited format.

       --append-terse
              Print   statistics   in   selected  mode  AND  terse,  semicolon-delimited  format.
              Deprecated, use --output-format instead to select multiple formats.

       --terse-version=version
              Set terse version output format (default `3', or `2', `4', `5').

       --version
              Print version information and exit.

       --help Print a summary of the command line options and exit.

       --cpuclock-test
              Perform test and validation of internal CPU clock.

       --crctest=[test]
              Test the speed of the built-in checksumming functions. If no argument is given, all
              of  them  are tested. Alternatively, a comma separated list can be passed, in which
              case the given ones are tested.

       --cmdhelp=command
              Print help information for command. May be `all' for all commands.

       --enghelp=[ioengine[,command]]
              List all commands defined by  ioengine,  or  print  help  for  command  defined  by
              ioengine. If no ioengine is given, list all available ioengines.

       --showcmd
              Convert given jobfiles to a set of command-line options.

       --readonly
              Turn on safety read-only checks, preventing writes and trims. The --readonly option
              is an extra safety guard to prevent users from accidentally  starting  a  write  or
              trim  workload when that is not desired. Fio will only modify the device under test
              if `rw=write/randwrite/rw/randrw/trim/randtrim/trimwrite' is given. This safety net
              can be used as an extra precaution.

       --eta=when
              Specifies  when  real-time  ETA  estimate  should be printed. when may be `always',
              `never' or `auto'. `auto' is the default, it  prints  ETA  when  requested  if  the
              output  is  a  TTY.  `always'  disregards  the  output  type,  and  prints ETA when
              requested. `never' never prints ETA.

       --eta-interval=time
              By default, fio requests client ETA status roughly every second. With this  option,
              the  interval is configurable. Fio imposes a minimum allowed time to avoid flooding
              the console, less than 250 msec is not supported.

       --eta-newline=time
              Force a new line for every time period passed. When the unit is omitted, the  value
              is interpreted in seconds.

       --status-interval=time
              Force  a  full status dump of cumulative (from job start) values at time intervals.
              This option does *not* provide per-period measurements. So values such as bandwidth
              are  running  averages.  When  the  time  unit  is  omitted, time is interpreted in
              seconds. Note that using this option with `--output-format=json' will yield  output
              that  technically isn't valid json, since the output will be collated sets of valid
              json. It will need to be split into valid sets of json after the run.

       --section=name
              Only run specified section name in job file. Multiple sections  can  be  specified.
              The  --section  option  allows one to combine related jobs into one file.  E.g. one
              job file could define light, moderate, and heavy sections. Tell fio to run only the
              "heavy"  section  by  giving  `--section=heavy'  command  line option. One can also
              specify the "write" operations in one section and  "verify"  operation  in  another
              section.  The  --section option only applies to job sections. The reserved *global*
              section is always parsed and used.

       --alloc-size=kb
              Allocate additional internal smalloc pools of size  kb  in  KiB.  The  --alloc-size
              option  increases  shared  memory  set aside for use by fio.  If running large jobs
              with randommap enabled, fio  can  run  out  of  memory.   Smalloc  is  an  internal
              allocator  for  shared  structures from a fixed size memory pool and can grow to 16
              pools. The pool size defaults  to  16MiB.   NOTE:  While  running  `.fio_smalloc.*'
              backing store files are visible in `/tmp'.

       --warnings-fatal
              All fio parser warnings are fatal, causing fio to exit with an error.

       --max-jobs=nr
              Set  the  maximum number of threads/processes to support to nr.  NOTE: On Linux, it
              may be necessary to increase the shared-memory limit (`/proc/sys/kernel/shmmax') if
              fio runs into errors while creating jobs.

       --server=args
              Start  a backend server, with args specifying what to listen to.  See CLIENT/SERVER
              section.

       --daemonize=pidfile
              Background a fio server, writing the pid to the given pidfile file.

       --client=hostname
              Instead of running the jobs locally, send and run them on the given hostname or set
              of hostnames. See CLIENT/SERVER section.

       --remote-config=file
              Tell fio server to load this local file.

       --idle-prof=option
              Report CPU idleness. option is one of the following:

                     calibrate
                            Run unit work calibration only and exit.

                     system Show aggregate system idleness and unit work.

                     percpu As system but also show per CPU idleness.

       --inflate-log=log
              Inflate and output compressed log.

       --trigger-file=file
              Execute trigger command when file exists.

       --trigger-timeout=time
              Execute trigger at this time.

       --trigger=command
              Set this command as local trigger.

       --trigger-remote=command
              Set this command as remote trigger.

       --aux-path=path
              Use  the  directory  specified  by  path  for  generated state files instead of the
              current working directory.

JOB FILE FORMAT

       Any parameters following the options will be assumed to be job files, unless they match  a
       job file parameter. Multiple job files can be listed and each job file will be regarded as
       a separate group. Fio will stonewall execution between each group.

       Fio accepts one or more job files describing what it is  supposed  to  do.  The  job  file
       format  is  the  classic  ini file, where the names enclosed in [] brackets define the job
       name. You are free to use any ASCII name you  want,  except  *global*  which  has  special
       meaning.  Following  the  job name is a sequence of zero or more parameters, one per line,
       that define the behavior of the job. If the first character in a line is a ';' or  a  '#',
       the entire line is discarded as a comment.

       A *global* section sets defaults for the jobs described in that file. A job may override a
       *global* section parameter, and a job file may even have several *global* sections  if  so
       desired. A job is only affected by a *global* section residing above it.

       The  --cmdhelp  option also lists all options. If used with an command argument, --cmdhelp
       will detail the given command.

       See the `examples/' directory for  inspiration  on  how  to  write  job  files.  Note  the
       copyright and license requirements currently apply to `examples/' files.

       Note that the maximum length of a line in the job file is 8192 bytes.

JOB FILE PARAMETERS

       Some parameters take an option of a given type, such as an integer or a string. Anywhere a
       numeric value is required, an arithmetic expression may be used, provided it is surrounded
       by parentheses. Supported operators are:

              addition (+)

              subtraction (-)

              multiplication (*)

              division (/)

              modulus (%)

              exponentiation (^)

       For  time values in expressions, units are microseconds by default. This is different than
       for time values not in expressions (not enclosed in parentheses).

PARAMETER TYPES

       The following parameter types are used.

       str    String. A sequence of alphanumeric characters.

       time   Integer with possible time suffix. Without a unit value is interpreted  as  seconds
              unless  otherwise  specified.  Accepts a suffix of 'd' for days, 'h' for hours, 'm'
              for minutes, 's' for seconds, 'ms'  (or  'msec')  for  milliseconds  and  'us'  (or
              'usec') for microseconds. For example, use 10m for 10 minutes.

       int    Integer.  A  whole number value, which may contain an integer prefix and an integer
              suffix.

                     [*integer prefix*] **number** [*integer suffix*]

              The optional *integer prefix* specifies the number's base. The default is  decimal.
              *0x* specifies hexadecimal.

              The  optional  *integer  suffix*  specifies  the  number's  units,  and includes an
              optional unit prefix and an optional unit. For quantities of data, the default unit
              is  bytes.  For  quantities  of  time, the default unit is seconds unless otherwise
              specified.

              With `kb_base=1000', fio follows international  standards  for  unit  prefixes.  To
              specify  power-of-10  decimal  values  defined in the International System of Units
              (SI):

                     K means kilo (K) or 1000
                     M means mega (M) or 1000**2
                     G means giga (G) or 1000**3
                     T means tera (T) or 1000**4
                     P means peta (P) or 1000**5

              To specify power-of-2 binary values defined in IEC 80000-13:

                     Ki means kibi (Ki) or 1024
                     Mi means mebi (Mi) or 1024**2
                     Gi means gibi (Gi) or 1024**3
                     Ti means tebi (Ti) or 1024**4
                     Pi means pebi (Pi) or 1024**5

              For Zone Block Device Mode:

                     z means Zone
              With `kb_base=1024' (the default),  the  unit  prefixes  are  opposite  from  those
              specified  in  the  SI and IEC 80000-13 standards to provide compatibility with old
              scripts. For example, 4k means 4096.

              For quantities of data, an optional unit of 'B' may be included (e.g., 'kB' is  the
              same as 'k').

              The  *integer suffix* is not case sensitive (e.g., m/mi mean mebi/mega, not milli).
              'b' and 'B' both mean byte, not bit.

              Examples with `kb_base=1000':

                     4 KiB: 4096, 4096b, 4096B, 4k, 4kb, 4kB, 4K, 4KB
                     1 MiB: 1048576, 1m, 1024k
                     1 MB: 1000000, 1mi, 1000ki
                     1 TiB: 1073741824, 1t, 1024m, 1048576k
                     1 TB: 1000000000, 1ti, 1000mi, 1000000ki

              Examples with `kb_base=1024' (default):

                     4 KiB: 4096, 4096b, 4096B, 4k, 4kb, 4kB, 4K, 4KB
                     1 MiB: 1048576, 1m, 1024k
                     1 MB: 1000000, 1mi, 1000ki
                     1 TiB: 1073741824, 1t, 1024m, 1048576k
                     1 TB: 1000000000, 1ti, 1000mi, 1000000ki

              To specify times (units are not case sensitive):

                     D means days
                     H means hours
                     M mean minutes
                     s or sec means seconds (default)
                     ms or msec means milliseconds
                     us or usec means microseconds

              `z' suffix specifies that the value is measured in zones.   Value  is  recalculated
              once block device's zone size becomes known.

              If  the  option  accepts  an upper and lower range, use a colon ':' or minus '-' to
              separate such values. See irange parameter type.   If  the  lower  value  specified
              happens to be larger than the upper value the two values are swapped.

       bool   Boolean.  Usually  parsed as an integer, however only defined for true and false (1
              and 0).

       irange Integer range with suffix. Allows value range to be given,  such  as  1024-4096.  A
              colon  may also be used as the separator, e.g. 1k:4k. If the option allows two sets
              of ranges, they can be specified with a ',' or '/'  delimiter:  1k-4k/8k-32k.  Also
              see int parameter type.

       float_list
              A list of floating point numbers, separated by a ':' character.

JOB PARAMETERS

       With the above in mind, here follows the complete list of fio job parameters.

   Units
       kb_base=int
              Select the interpretation of unit prefixes in input parameters.

                     1000   Inputs comply with IEC 80000-13 and the International System of Units
                            (SI). Use:

                            - power-of-2 values with IEC prefixes (e.g., KiB)
                            - power-of-10 values with SI prefixes (e.g., kB)

                     1024   Compatibility mode (default). To avoid breaking old scripts:

                            - power-of-2 values with SI prefixes
                            - power-of-10 values with IEC prefixes

              See bs for more details on input parameters.

              Outputs always use correct prefixes. Most outputs include both side-by-side, like:

                     bw=2383.3kB/s (2327.4KiB/s)

              If only one value is reported, then kb_base selects the one to use:

                     1000 -- SI prefixes
                     1024 -- IEC prefixes

       unit_base=int
              Base unit for reporting. Allowed values are:

                     0      Use auto-detection (default).

                     8      Byte based.

                     1      Bit based.

   Job description
       name=str
              ASCII name of the job. This may be used to override the name  printed  by  fio  for
              this  job.  Otherwise  the job name is used. On the command line this parameter has
              the special purpose of also signaling the start of a new job.

       description=str
              Text description of the job. Doesn't do anything except dump this text  description
              when this job is run. It's not parsed.

       loops=int
              Run  the  specified  number  of  iterations  of  this  job. Used to repeat the same
              workload a given number of times. Defaults to 1.

       numjobs=int
              Create the specified number of clones of this job. Each clone of job is spawned  as
              an  independent  thread  or  process.  May  be  used  to  setup  a larger number of
              threads/processes doing the same thing. Each thread is reported separately; to  see
              statistics  for  all  clones  as  a  whole, use group_reporting in conjunction with
              new_group.  See --max-jobs. Default: 1.

   Time related parameters
       runtime=time
              Limit runtime. The test will run until it completes the configured I/O workload  or
              until  it has run for this specified amount of time, whichever occurs first. It can
              be quite hard to determine for how long a specified job will run, so this parameter
              is  handy  to cap the total runtime to a given time.  When the unit is omitted, the
              value is interpreted in seconds.

       time_based
              If set, fio will run for the duration of the runtime specified even if the  file(s)
              are  completely read or written. It will simply loop over the same workload as many
              times as the runtime allows.

       startdelay=irange(int)
              Delay the start of job for the specified amount of time. Can be a single value or a
              range.  When given as a range, each thread will choose a value randomly from within
              the range. Value is in seconds if a unit is omitted.

       ramp_time=time
              If set, fio will run the specified workload for this amount of time before  logging
              any  performance  numbers.  Useful  for  letting  performance settle before logging
              results, thus minimizing the runtime required for stable  results.  Note  that  the
              ramp_time  is  considered  lead  in time for a job, thus it will increase the total
              runtime if a special timeout or runtime is specified. When the unit is omitted, the
              value is given in seconds.

       clocksource=str
              Use the given clocksource as the base of timing. The supported options are:

                     gettimeofday
                            gettimeofday(2)

                     clock_gettime
                            clock_gettime(2)

                     cpu    Internal CPU clock source

              cpu  is the preferred clocksource if it is reliable, as it is very fast (and fio is
              heavy on time calls). Fio will automatically use this clocksource if it's supported
              and  considered reliable on the system it is running on, unless another clocksource
              is specifically set. For x86/x86-64 CPUs, this means supporting TSC Invariant.

       gtod_reduce=bool
              Enable all of the gettimeofday(2)  reducing  options  (disable_clat,  disable_slat,
              disable_bw_measurement)  plus  reduce  precision  of the timeout somewhat to really
              shrink the gettimeofday(2) call count. With this option enabled, we only  do  about
              0.4%  of  the  gettimeofday(2)  calls  we  would  have done if all time keeping was
              enabled.

       gtod_cpu=int
              Sometimes it's cheaper to dedicate a single thread of execution to just getting the
              current   time.   Fio   (and   databases,  for  instance)  are  very  intensive  on
              gettimeofday(2) calls. With this option, you  can  set  one  CPU  aside  for  doing
              nothing  but  logging  current  time  to  a  shared memory location. Then the other
              threads/processes that run I/O workloads need only copy that  segment,  instead  of
              entering  the kernel with a gettimeofday(2) call. The CPU set aside for doing these
              time calls will be excluded from other uses. Fio will manually clear  it  from  the
              CPU mask of other jobs.

   Target file/device
       directory=str
              Prefix  filenames  with this directory. Used to place files in a different location
              than `./'. You can specify a number of directories by separating the names  with  a
              ':' character. These directories will be assigned equally distributed to job clones
              created by numjobs as long as they  are  using  generated  filenames.  If  specific
              filename(s)  are  set fio will use the first listed directory, and thereby matching
              the filename semantic (which generates a file for each clone if not specified,  but
              lets all clones use the same file if set).

              See  the filename option for information on how to escape ':' characters within the
              directory path itself.

              Note: To  control  the  directory  fio  will  use  for  internal  state  files  use
              --aux-path.

       filename=str
              Fio  normally  makes  up  a filename based on the job name, thread number, and file
              number (see filename_format). If you want to share files between threads in  a  job
              or  several  jobs  with  fixed  file  paths, specify a filename for each of them to
              override the default. If the ioengine is file based, you can specify  a  number  of
              files  by  separating  the  names  with a ':' colon. So if you wanted a job to open
              `/dev/sda'  and  `/dev/sdb'   as   the   two   working   files,   you   would   use
              `filename=/dev/sda:/dev/sdb'.   This  also  means  that  whenever  this  option  is
              specified, nrfiles is ignored. The size of regular files specified by  this  option
              will  be  size  divided  by number of files unless an explicit size is specified by
              filesize.

              Each colon in the wanted path must be escaped with a '\' character.  For  instance,
              if     the     path     is     `/dev/dsk/foo@3,0:c'     then    you    would    use
              `filename=/dev/dsk/foo@3,0\:c' and if the path is `F:\filename' then you would  use
              `filename=F\:\filename'.

              On Windows, disk devices are accessed as `\\.\PhysicalDrive0' for the first device,
              `\\.\PhysicalDrive1' for the second etc.  Note: Windows and FreeBSD  prevent  write
              access to areas of the disk containing in-use data (e.g. filesystems).

              The  filename `-' is a reserved name, meaning *stdin* or *stdout*. Which of the two
              depends on the read/write direction set.

       filename_format=str
              If sharing multiple files between  jobs,  it  is  usually  necessary  to  have  fio
              generate  the  exact names that you want. By default, fio will name a file based on
              the default file format specification of `jobname.jobnumber.filenumber'. With  this
              option,  that  can  be  customized.  Fio  will  recognize and replace the following
              keywords in this string:

                     $jobname
                            The name of the worker thread or process.

                     $clientuid
                            IP of the fio process when using client/server mode.

                     $jobnum
                            The incremental number of the worker thread or process.

                     $filenum
                            The incremental number of the file for that worker thread or process.

              To have dependent jobs share a set of files, this option can be  set  to  have  fio
              generate   filenames   that   are   shared   between  the  two.  For  instance,  if
              `testfiles.$filenum' is specified,  file  number  4  for  any  job  will  be  named
              `testfiles.4'.  The default of `$jobname.$jobnum.$filenum' will be used if no other
              format specifier is given.

              If you specify a path then the directories will be created up to the main directory
              for  the  file.  So for example if you specify `a/b/c/$jobnum` then the directories
              a/b/c will be created before the file setup  part  of  the  job.   If  you  specify
              directory then the path will be relative that directory, otherwise it is treated as
              the absolute path.

       unique_filename=bool
              To avoid collisions between  networked  clients,  fio  defaults  to  prefixing  any
              generated  filenames  (with  a  directory  specified) with the source of the client
              connecting. To disable this behavior, set this option to 0.

       opendir=str
              Recursively open any files below directory str.

       lockfile=str
              Fio defaults to not locking any files before it does I/O to them. If a file or file
              descriptor  is  shared,  fio  can serialize I/O to that file to make the end result
              consistent. This is usual for emulating real workloads that share files.  The  lock
              modes are:

                     none   No locking. The default.

                     exclusive
                            Only  one  thread  or  process  may  do  I/O at a time, excluding all
                            others.

                     readwrite
                            Read-write locking on the file. Many readers may access the  file  at
                            the same time, but writes get exclusive access.

       nrfiles=int
              Number  of files to use for this job. Defaults to 1. The size of files will be size
              divided by this unless explicit size is specified by filesize.  Files  are  created
              for  each  thread separately, and each file will have a file number within its name
              by default, as explained in filename section.

       openfiles=int
              Number of files to keep open at the same time. Defaults to the same as nrfiles, can
              be set smaller to limit the number simultaneous opens.

       file_service_type=str
              Defines  how fio decides which file from a job to service next. The following types
              are defined:

                     random Choose a file at random.

                     roundrobin
                            Round robin over opened files. This is the default.

                     sequential
                            Finish one file before moving on to  the  next.  Multiple  files  can
                            still be open depending on openfiles.

                     zipf   Use a Zipf distribution to decide what file to access.

                     pareto Use a Pareto distribution to decide what file to access.

                     normal Use a Gaussian (normal) distribution to decide what file to access.

                     gauss  Alias for normal.

              For  random,  roundrobin, and sequential, a postfix can be appended to tell fio how
              many I/Os to issue  before  switching  to  a  new  file.  For  example,  specifying
              `file_service_type=random:8' would cause fio to issue 8 I/Os before selecting a new
              file at random. For the non-uniform distributions, a floating point postfix can  be
              given  to  influence  how the distribution is skewed. See random_distribution for a
              description of how that would work.

       ioscheduler=str
              Attempt to switch the device hosting the file to the specified I/O scheduler before
              running.  If  the  file is a pipe, a character device file or if device hosting the
              file could not be determined, this option is ignored.

       create_serialize=bool
              If true, serialize the file creation for the jobs.  This  may  be  handy  to  avoid
              interleaving  of  data  files,  which may greatly depend on the filesystem used and
              even the number of processors in the system. Default: true.

       create_fsync=bool
              fsync(2) the data file after creation. This is the default.

       create_on_open=bool
              If true, don't pre-create files but allow the job's open() to create  a  file  when
              it's  time to do I/O. Default: false -- pre-create all necessary files when the job
              starts.

       create_only=bool
              If true, fio will only run the setup phase of the job. If files need to be laid out
              or  updated  on  disk,  only  that  will be done -- the actual job contents are not
              executed. Default: false.

       allow_file_create=bool
              If true, fio is permitted to create files as part of its workload. If  this  option
              is false, then fio will error out if the files it needs to use don't already exist.
              Default: true.

       allow_mounted_write=bool
              If this isn't set, fio will abort jobs that are destructive (e.g.  that  write)  to
              what  appears  to be a mounted device or partition. This should help catch creating
              inadvertently destructive tests, not realizing that the test will destroy  data  on
              the  mounted  file  system.  Note that some platforms don't allow writing against a
              mounted device regardless of this option. Default: false.

       pre_read=bool
              If this is given, files will be pre-read into memory before starting the given  I/O
              operation.  This will also clear the invalidate flag, since it is pointless to pre-
              read and then drop the cache. This will only work for I/O engines  that  are  seek-
              able,  since  they allow you to read the same data multiple times. Thus it will not
              work on non-seekable I/O engines (e.g. network, splice). Default: false.

       unlink=bool
              Unlink the job files when done. Not the default, as repeated runs of that job would
              then waste time recreating the file set again and again. Default: false.

       unlink_each_loop=bool
              Unlink job files after each iteration or loop. Default: false.

       zonemode=str
              Accepted values are:

                     none   The  zonerange,  zonesize  zonecapacity  and  zoneskip parameters are
                            ignored.

                     strided
                            I/O  happens  in  a  single  zone  until  zonesize  bytes  have  been
                            transferred.   After  that  number  of  bytes  has  been  transferred
                            processing of the next zone starts.  The  zonecapacity  parameter  is
                            ignored.

                     zbd    Zoned  block device mode. I/O happens sequentially in each zone, even
                            if random I/O has been selected. Random I/O happens across all  zones
                            instead  of being restricted to a single zone.  Trim is handled using
                            a zone reset operation.  Trim  only  considers  non-empty  sequential
                            write required and sequential write preferred zones.

       zonerange=int
              For  zonemode=strided,  this  is  the  size of a single zone. See also zonesize and
              zoneskip.

              For zonemode=zbd, this parameter is ignored.

       zonesize=int
              For zonemode=strided, this is the number  of  bytes  to  transfer  before  skipping
              zoneskip bytes. If this parameter is smaller than zonerange then only a fraction of
              each zone with zonerange bytes will be accessed.  If this parameter is larger  than
              zonerange  then  each  zone  will be accessed multiple times before skipping to the
              next zone.

              For zonemode=zbd, this is the size of a single zone.  The  zonerange  parameter  is
              ignored  in  this  mode.  For  a  job accessing a zoned block device, the specified
              zonesize must be 0 or equal to the device zone size. For a regular block device  or
              file, the specified zonesize must be at least 512B.

       zonecapacity=int
              For  zonemode=zbd,  this  defines  the  capacity  of  a  single  zone, which is the
              accessible area starting from the zone start address. This parameter  only  applies
              when  using  zonemode=zbd  in  combination  with  regular  block  devices.   If not
              specified it defaults to the zone size. If the  target  device  is  a  zoned  block
              device,  the  zone capacity is obtained from the device information and this option
              is ignored.

       zoneskip=int[z]
              For zonemode=strided, the number of bytes to skip after zonesize bytes of data have
              been transferred.

              For zonemode=zbd, the zonesize aligned number of bytes to skip once a zone is fully
              written (write workloads) or all written data in the  zone  have  been  read  (read
              workloads).  This  parameter is valid only for sequential workloads and ignored for
              random workloads. For read workloads, see also read_beyond_wp.

       read_beyond_wp=bool
              This parameter applies to zonemode=zbd only.

              Zoned block devices are block devices that consist of multiple zones. Each zone has
              a  type, e.g. conventional or sequential. A conventional zone can be written at any
              offset that is a multiple of the block  size.  Sequential  zones  must  be  written
              sequentially. The position at which a write must occur is called the write pointer.
              A zoned block device can be either host managed or host  aware.  For  host  managed
              devices  the  host must ensure that writes happen sequentially. Fio recognizes host
              managed devices and serializes writes to sequential zones for these devices.

              If a read occurs in a sequential zone beyond the write pointer then the zoned block
              device  will  complete  the  read without reading any data from the storage medium.
              Since such reads lead to unrealistically high bandwidth and IOPS numbers  fio  only
              reads beyond the write pointer if explicitly told to do so. Default: false.

       max_open_zones=int
              A  zone  of  a zoned block device is in the open state when it is partially written
              (i.e. not all sectors of the zone have been written). Zoned block devices may  have
              limit  a on the total number of zones that can be simultaneously in the open state,
              that is,  the  number  of  zones  that  can  be  written  to  simultaneously.   The
              max_open_zones  parameter  limits  the  number of zones to which write commands are
              issued by all fio jobs, that is, limits the number of zones that  will  be  in  the
              open  state.  This  parameter  is  relevant  only  if the zonemode=zbd is used. The
              default value is always equal to maximum number of open zones of the  target  zoned
              block device and a value higher than this limit cannot be specified by users unless
              the option ignore_zone_limits is specified. When ignore_zone_limits is specified or
              the target device has no limit on the number of zones that can be in an open state,
              max_open_zones can specify 0 to disable any limit on the number of zones  that  can
              be simultaneously written to by all jobs.

       job_max_open_zones=int
              In  the  same manner as max_open_zones, limit the number of open zones per fio job,
              that is, the number of zones that a single job can simultaneously write to. A value
              of zero indicates no limit. Default: zero.

       ignore_zone_limits=bool
              If  this  option is used, fio will ignore the maximum number of open zones limit of
              the zoned block device in use, thus allowing the option max_open_zones value to  be
              larger than the device reported limit. Default: false.

       zone_reset_threshold=float
              A  number  between  zero  and  one that indicates the ratio of written bytes in the
              zones with write pointers in the IO range to the size of the IO range. When current
              ratio  is  above  this  ratio, zones are reset periodically as zone_reset_frequency
              specifies. If there are multiple jobs when using this option, the IO range for  all
              write jobs has to be the same.

       zone_reset_frequency=float
              A  number  between  zero  and  one  that indicates how often a zone reset should be
              issued if the zone reset threshold has been exceeded. A  zone  reset  is  submitted
              after  each  (1  /  zone_reset_frequency)  write  requests.  This  and the previous
              parameter can be used to simulate garbage collection activity.

   I/O type
       direct=bool
              If value is true, use non-buffered I/O. This is usually O_DIRECT. Note that OpenBSD
              and  ZFS  on Solaris don't support direct I/O. On Windows the synchronous ioengines
              don't support direct I/O. Default: false.

       buffered=bool
              If value is true, use buffered I/O. This is the  opposite  of  the  direct  option.
              Defaults to true.

       readwrite=str, rw=str
              Type of I/O pattern. Accepted values are:

                     read   Sequential reads.

                     write  Sequential writes.

                     trim   Sequential  trims  (Linux  block  devices  and SCSI character devices
                            only).

                     randread
                            Random reads.

                     randwrite
                            Random writes.

                     randtrim
                            Random trims (Linux block devices and SCSI character devices only).

                     rw,readwrite
                            Sequential mixed reads and writes.

                     randrw Random mixed reads and writes.

                     trimwrite
                            Sequential trim+write sequences. Blocks will be trimmed  first,  then
                            the same blocks will be written to. So if `io_size=64K' is specified,
                            Fio will trim a total of 64K bytes and also write 64K  bytes  on  the
                            same   trimmed   blocks.  This  behaviour  will  be  consistent  with
                            `number_ios' or other Fio options limiting the total bytes or  number
                            of I/O's.

                     randtrimwrite
                            Like  trimwrite  ,  but  uses  random  offsets rather than sequential
                            writes.

              Fio defaults to read if the option is not specified. For the mixed I/O  types,  the
              default  is  to  split them 50/50. For certain types of I/O the result may still be
              skewed a bit, since the speed may be different.

              It is possible to specify the number of I/Os to do before getting a new  offset  by
              appending  `:<nr>' to the end of the string given. For a random read, it would look
              like `rw=randread:8' for passing in an offset modifier with a value of  8.  If  the
              suffix  is used with a sequential I/O pattern, then the `<nr>' value specified will
              be added to  the  generated  offset  for  each  I/O  turning  sequential  I/O  into
              sequential  I/O  with  holes.   For  instance, using `rw=write:4k' will skip 4k for
              every write. Also see the rw_sequencer option.

       rw_sequencer=str
              If an offset modifier is given by appending a number to  the  `rw=str'  line,  then
              this  option  controls  how  that  number  modifies the I/O offset being generated.
              Accepted values are:

                     sequential
                            Generate sequential offset.

                     identical
                            Generate the same offset.

              sequential is only useful for random I/O, where fio would normally generate  a  new
              random offset for every I/O. If you append e.g. 8 to randread, i.e. `rw=randread:8'
              you would get a new random offset for every 8 I/Os. The result would be a  sequence
              of  8  sequential  offsets with a random starting point.  However this behavior may
              change if a sequential I/O reaches end of the file. As sequential  I/O  is  already
              sequential,  setting  sequential  for  that  would  not  result  in any difference.
              identical behaves in a similar fashion, except it sends the same offset 8 number of
              times before generating a new offset.

              Example #1:

                     rw=randread:8
                     rw_sequencer=sequential
                     bs=4k

              The  generated sequence of offsets will look like this: 4k, 8k, 12k, 16k, 20k, 24k,
              28k, 32k, 92k, 96k, 100k, 104k, 108k, 112k, 116k, 120k, 48k, 52k ...

              Example #2:

                     rw=randread:8
                     rw_sequencer=identical
                     bs=4k

              The generated sequence of offsets will look like this: 4k, 4k, 4k, 4k, 4k, 4k,  4k,
              4k, 92k, 92k, 92k, 92k, 92k, 92k, 92k, 92k, 48k, 48k, 48k ...

       unified_rw_reporting=str
              Fio  normally reports statistics on a per data direction basis, meaning that reads,
              writes, and trims are accounted and reported  separately.  This  option  determines
              whether  fio  reports  the  results  normally, summed together, or as both options.
              Accepted values are:

              none   Normal statistics reporting.

              mixed  Statistics are summed per data direction and reported together.

              both   Statistics are reported normally, followed by the mixed statistics.

              0      Backward-compatible alias for none.

              1      Backward-compatible alias for mixed.

              2      Alias for both.

       randrepeat=bool
              Seed all random number generators in a predictable way so the pattern is repeatable
              across runs. Default: true.

       allrandrepeat=bool
              Alias for randrepeat. Default: true.

       randseed=int
              Seed  the  random number generators based on this seed value, to be able to control
              what sequence of output is being generated. If not set, the random sequence depends
              on the randrepeat setting.

       fallocate=str
              Whether pre-allocation is performed when laying down files.  Accepted values are:

                     none   Do not pre-allocate space.

                     native Use  a  platform's  native  pre-allocation call but fall back to none
                            behavior if it fails/is not implemented.

                     posix  Pre-allocate via posix_fallocate(3).

                     keep   Pre-allocate via fallocate(2) with FALLOC_FL_KEEP_SIZE set.

                     truncate
                            Extend file to final size using ftruncate|(2) instead of allocating.

                     0      Backward-compatible alias for none.

                     1      Backward-compatible alias for posix.

              May not be available on all supported platforms. keep is only available  on  Linux.
              If  using  ZFS  on  Solaris this cannot be set to posix because ZFS doesn't support
              pre-allocation. Default: native if any pre-allocation methods except  truncate  are
              available, none if not.

              Note  that using truncate on Windows will interact surprisingly with non-sequential
              write patterns. When writing to a file that has been extended by setting  the  end-
              of-file  information, Windows will backfill the unwritten portion of the file up to
              that offset with zeroes before issuing the new write.  This  means  that  a  single
              small  write  to  the  end of an extended file will stall until the entire file has
              been filled with zeroes.

       fadvise_hint=str
              Use posix_fadvise(2) or posix_madvise(2) to advise the kernel what I/O patterns are
              likely to be issued. Accepted values are:

                     0      Backwards compatible hint for "no hint".

                     1      Backwards  compatible  hint for "advise with fio workload type". This
                            uses FADV_RANDOM for a random workload,  and  FADV_SEQUENTIAL  for  a
                            sequential workload.

                     sequential
                            Advise using FADV_SEQUENTIAL.

                     random Advise using FADV_RANDOM.

                     noreuse
                            Advise  using  FADV_NOREUSE.  This  may  be  a  no-op  on older Linux
                            kernels. Since Linux 6.3, it provides a hint to  the  LRU  algorithm.
                            See the posix_fadvise(2) man page.

       write_hint=str
              Use  fcntl(2)  to  advise  the  kernel  what life time to expect from a write. Only
              supported on Linux, as of version 4.13. Accepted values are:

                     none   No particular life time associated with this file.

                     short  Data written to this file has a short life time.

                     medium Data written to this file has a medium life time.

                     long   Data written to this file has a long life time.

                     extreme
                            Data written to this file has a very long life time.

              The values are all relative to each  other,  and  no  absolute  meaning  should  be
              associated with them.

       offset=int[%|z]
              Start  I/O  at  the  provided  offset  in the file, given as either a fixed size in
              bytes, zones or a percentage. If a percentage is given, the generated  offset  will
              be  aligned  to  the minimum blocksize or to the value of offset_align if provided.
              Data before the given offset will not be touched. This effectively  caps  the  file
              size  at `real_size - offset'. Can be combined with size to constrain the start and
              end range of the I/O workload.  A percentage can be specified by a number between 1
              and  100  followed  by  '%', for example, `offset=20%' to specify 20%. In ZBD mode,
              value can be set as number of zones using 'z'.

       offset_align=int
              If set to non-zero value, the byte offset  generated  by  a  percentage  offset  is
              aligned  upwards  to  this value. Defaults to 0 meaning that a percentage offset is
              aligned to the minimum block size.

       offset_increment=int[%|z]
              If this is provided, then the real offset  becomes  `offset  +  offset_increment  *
              thread_number',  where  the  thread  number  is  a  counter that starts at 0 and is
              incremented for each sub-job (i.e. when numjobs option is specified).  This  option
              is  useful  if  there  are  several jobs which are intended to operate on a file in
              parallel  disjoint  segments,  with  even  spacing  between  the  starting  points.
              Percentages  can  be used for this option.  If a percentage is given, the generated
              offset will be aligned to the minimum blocksize or to the value of offset_align  if
              provided.In ZBD mode, value can be set as number of zones using 'z'.

       number_ios=int
              Fio will normally perform I/Os until it has exhausted the size of the region set by
              size, or if it exhaust the allocated time (or hits an error condition).  With  this
              setting,  the range/size can be set independently of the number of I/Os to perform.
              When fio reaches this number, it will exit normally and report  status.  Note  that
              this  does not extend the amount of I/O that will be done, it will only stop fio if
              this condition is met before other end-of-job criteria.

       fsync=int
              If writing to a file, issue an fsync(2) (or its equivalent) of the dirty  data  for
              every  number of blocks given. For example, if you give 32 as a parameter, fio will
              sync the file after every 32 writes issued. If fio is using  non-buffered  I/O,  we
              may  not  sync the file. The exception is the sg I/O engine, which synchronizes the
              disk cache anyway. Defaults to 0, which means fio does not periodically  issue  and
              wait for a sync to complete. Also see end_fsync and fsync_on_close.

       fdatasync=int
              Like  fsync  but  uses  fdatasync(2)  to only sync data and not metadata blocks. In
              Windows, DragonFlyBSD or OSX there is no fdatasync(2) so this falls back  to  using
              fsync(2).   Defaults to 0, which means fio does not periodically issue and wait for
              a data-only sync to complete.

       write_barrier=int
              Make every N-th write a barrier write.

       sync_file_range=str:int
              Use sync_file_range(2) for every int number of write  operations.  Fio  will  track
              range  of writes that have happened since the last sync_file_range(2) call. str can
              currently be one or more of:

                     wait_before
                            SYNC_FILE_RANGE_WAIT_BEFORE

                     write  SYNC_FILE_RANGE_WRITE

                     wait_after
                            SYNC_FILE_RANGE_WRITE_AFTER

              So   if   you   do    `sync_file_range=wait_before,write:8',    fio    would    use
              `SYNC_FILE_RANGE_WAIT_BEFORE  | SYNC_FILE_RANGE_WRITE' for every 8 writes. Also see
              the sync_file_range(2) man page. This option is Linux specific.

       overwrite=bool
              If true, writes to a file will always overwrite existing data. If the file  doesn't
              already exist, it will be created before the write phase begins. If the file exists
              and is large enough for the specified write phase, nothing will be  done.  Default:
              false.

       end_fsync=bool
              If true, fsync(2) file contents when a write stage has completed.  Default: false.

       fsync_on_close=bool
              If  true,  fio  will fsync(2) a dirty file on close. This differs from end_fsync in
              that it will happen on every file close, not just at the end of the  job.  Default:
              false.

       rwmixread=int
              Percentage of a mixed workload that should be reads. Default: 50.

       rwmixwrite=int
              Percentage  of  a  mixed  workload  that  should  be  writes. If both rwmixread and
              rwmixwrite is given and the values do not add up to 100%, the  latter  of  the  two
              will  be  used to override the first. This may interfere with a given rate setting,
              if fio is asked to limit reads or writes to a certain rate. If that  is  the  case,
              then the distribution may be skewed. Default: 50.

       random_distribution=str:float[:float][,str:float][,str:float]
              By  default,  fio  will  use a completely uniform random distribution when asked to
              perform random I/O. Sometimes it is useful to skew  the  distribution  in  specific
              ways,  ensuring  that some parts of the data is more hot than others.  fio includes
              the following distribution models:

                     random Uniform random distribution

                     zipf   Zipf distribution

                     pareto Pareto distribution

                     normal Normal (Gaussian) distribution

                     zoned  Zoned   random   distribution   zoned_abs   Zoned   absolute   random
                            distribution

              When  using  a zipf or pareto distribution, an input value is also needed to define
              the access pattern. For zipf, this is the  `Zipf  theta'.   For  pareto,  it's  the
              `Pareto  power'.  Fio  includes  a  test  program,  fio-genzipf,  that  can be used
              visualize what the given input values will yield in terms  of  hit  rates.  If  you
              wanted    to    use    zipf    with    a    `theta'   of   1.2,   you   would   use
              `random_distribution=zipf:1.2' as the option. If a non-uniform model is  used,  fio
              will  disable  use  of  the  random  map.  For  the  normal  distribution, a normal
              (Gaussian) deviation is supplied as a value between 0 and 100.

              The second, optional float is allowed for pareto, zipf and normal distributions. It
              allows  one  to  set base of distribution in non-default place, giving more control
              over most probable outcome. This value is in range [0-1]  which  maps  linearly  to
              range of possible random values.  Defaults are: random for pareto and zipf, and 0.5
              for normal.  If you wanted to use zipf with a `theta` of 1.2  centered  on  1/4  of
              allowed value range, you would use `random_distribution=zipf:1.2:0.25`.

              For  a  zoned  distribution, fio supports specifying percentages of I/O access that
              should fall within what range of the file or device. For example, given a  criteria
              of:

                     60% of accesses should be to the first 10%
                     30% of accesses should be to the next 20%
                     8% of accesses should be to the next 30%
                     2% of accesses should be to the next 40%

              we  can  define  that through zoning of the random accesses. For the above example,
              the user would do:

                     random_distribution=zoned:60/10:30/20:8/30:2/40

              A zoned_abs distribution works exactly like thezoned, except that it takes absolute
              sizes.  For  example,  let's  say  you  wanted  to  define  access according to the
              following criteria:

                     60% of accesses should be to the first 20G
                     30% of accesses should be to the next 100G
                     10% of accesses should be to the next 500G

              we can define an absolute zoning distribution with:

                     random_distribution=zoned:60/10:30/20:8/30:2/40

              For both zoned and zoned_abs, fio supports defining up to 256 separate zones.

              Similarly to how bssplit works for setting ranges and percentages of  block  sizes.
              Like bssplit, it's possible to specify separate zones for reads, writes, and trims.
              If just one set is given, it'll apply to all of them.

       percentage_random=int[,int][,int]
              For a random workload, set how big a percentage should be random. This defaults  to
              100%,  in which case the workload is fully random. It can be set from anywhere from
              0 to 100. Setting it to 0 would make the workload fully sequential. Any setting  in
              between  will  result  in  a  random mix of sequential and random I/O, at the given
              percentages. Comma-separated values may be specified for reads, writes,  and  trims
              as described in blocksize.

       norandommap
              Normally  fio  will  cover  every  block of the file when doing random I/O. If this
              option is given, fio will just get a new random offset without looking at past  I/O
              history.  This  means  that  some  blocks may not be read or written, and that some
              blocks may be read/written more than once. If this option is used with  verify  and
              multiple   blocksizes  (via  bsrange),  only  intact  blocks  are  verified,  i.e.,
              partially-overwritten blocks are ignored.  With an async  I/O  engine  and  an  I/O
              depth  >  1,  it  is possible for the same block to be overwritten, which can cause
              verification errors.  Either do not use norandommap in this case, or also  use  the
              lfsr random generator.

       softrandommap=bool
              See  norandommap.  If  fio  runs  with the random block map enabled and it fails to
              allocate the map, if this option is set it will continue  without  a  random  block
              map.  As  coverage  will  not  be  as  complete as with random maps, this option is
              disabled by default.

       random_generator=str
              Fio supports the following engines for generating I/O offsets for random I/O:

                     tausworthe
                            Strong 2^88 cycle random number generator.

                     lfsr   Linear feedback shift register generator.

                     tausworthe64
                            Strong 64-bit 2^258 cycle random number generator.

              tausworthe is a strong random number generator, but it  requires  tracking  on  the
              side  if  we  want  to  ensure  that  blocks  are  only  read or written once. lfsr
              guarantees that we never generate  the  same  offset  twice,  and  it's  also  less
              computationally  expensive.  It's  not a true random generator, however, though for
              I/O purposes it's typically good enough. lfsr only works with single  block  sizes,
              not with workloads that use multiple block sizes. If used with such a workload, fio
              may read or write some blocks multiple times.  The  default  value  is  tausworthe,
              unless  the  required  space  exceeds 2^32 blocks. If it does, then tausworthe64 is
              selected automatically.

   Block size
       blocksize=int[,int][,int], bs=int[,int][,int]
              The block size in bytes used for I/O units. Default: 4096. A single  value  applies
              to  reads,  writes,  and  trims. Comma-separated values may be specified for reads,
              writes, and trims. A value not terminated in a comma applies to  subsequent  types.
              Examples:

                     bs=256k        means 256k for reads, writes and trims.
                     bs=8k,32k      means 8k for reads, 32k for writes and trims.
                     bs=8k,32k,     means 8k for reads, 32k for writes, and default for trims.
                     bs=,8k         means default for reads, 8k for writes and trims.
                     bs=,8k,         means  default  for  reads,  8k  for writes, and default for
                     trims.

       blocksize_range=irange[,irange][,irange], bsrange=irange[,irange][,irange]
              A range of block sizes in bytes for I/O units. The issued I/O unit will always be a
              multiple  of  the minimum size, unless blocksize_unaligned is set.  Comma-separated
              ranges may be specified for reads, writes, and trims  as  described  in  blocksize.
              Example:

                     bsrange=1k-4k,2k-8k

       bssplit=str[,str][,str]
              Sometimes  you  want even finer grained control of the block sizes issued, not just
              an even split between them. This option allows you to weight various  block  sizes,
              so  that you are able to define a specific amount of block sizes issued. The format
              for this option is:

                     bssplit=blocksize/percentage:blocksize/percentage

              for as many block sizes as needed. So if you want to define a workload that has 50%
              64k blocks, 10% 4k blocks, and 40% 32k blocks, you would write:

                     bssplit=4k/10:64k/50:32k/40

              Ordering  does  not  matter.  If the percentage is left blank, fio will fill in the
              remaining values evenly. So a bssplit option like this one:

                     bssplit=4k/50:1k/:32k/

              would have 50% 4k ios, and 25% 1k and 32k ios. The percentages  always  add  up  to
              100, if bssplit is given a range that adds up to more, it will error out.

              Comma-separated  values  may be specified for reads, writes, and trims as described
              in blocksize.

              If you want a workload that has 50% 2k reads and 50% 4k reads, while having 90%  4k
              writes and 10% 8k writes, you would specify:

                     bssplit=2k/50:4k/50,4k/90:8k/10

              Fio supports defining up to 64 different weights for each data direction.

       blocksize_unaligned, bs_unaligned
              If  set,  fio  will  issue I/O units with any size within blocksize_range, not just
              multiples of the minimum size. This typically won't work with direct I/O,  as  that
              normally requires sector alignment.

       bs_is_seq_rand=bool
              If  this  option  is  set, fio will use the normal read,write blocksize settings as
              sequential,random blocksize settings instead. Any random read or write will use the
              WRITE  blocksize  settings,  and  any  sequential  read  or write will use the READ
              blocksize settings.

       blockalign=int[,int][,int], ba=int[,int][,int]
              Boundary to which fio will align random  I/O  units.  Default:  blocksize.  Minimum
              alignment  is typically 512b for using direct I/O, though it usually depends on the
              hardware block size. This option is mutually exclusive with using a random map  for
              files, so it will turn off that option. Comma-separated values may be specified for
              reads, writes, and trims as described in blocksize.

   Buffers and memory
       zero_buffers
              Initialize buffers with all zeros. Default: fill buffers with random data.

       refill_buffers
              If this option is given, fio will refill the  I/O  buffers  on  every  submit.  The
              default  is  to  only fill it at init time and reuse that data. Only makes sense if
              zero_buffers  isn't  specified,  naturally.  If  data  verification   is   enabled,
              refill_buffers is also automatically enabled.

       scramble_buffers=bool
              If  refill_buffers  is  too costly and the target is using data deduplication, then
              setting this option will slightly modify the I/O buffer contents to  defeat  normal
              de-dupe  attempts.  This  is  not  enough  to  defeat more clever block compression
              attempts, but it will stop naive dedupe of blocks. Default: true.

       buffer_compress_percentage=int
              If this is set, then fio will attempt to provide I/O  buffer  content  (on  WRITEs)
              that  compresses to the specified level. Fio does this by providing a mix of random
              data followed by fixed pattern data. The fixed pattern  is  either  zeros,  or  the
              pattern specified by buffer_pattern. If the buffer_pattern option is used, it might
              skew the compression ratio slightly. Setting buffer_compress_percentage to a  value
              other  than  100  will also enable refill_buffers in order to reduce the likelihood
              that adjacent blocks are so similar that they over compress when seen together. See
              buffer_compress_chunk  for  how  to  set  a  finer  or  coarser  granularity of the
              random/fixed data regions. Defaults to unset i.e., buffer data will not  adhere  to
              any compression level.

       buffer_compress_chunk=int
              This  setting  allows  fio  to  manage how big the random/fixed data region is when
              using buffer_compress_percentage. When buffer_compress_chunk is set  to  some  non-
              zero  value  smaller  than  the  block size, fio can repeat the random/fixed region
              throughout the I/O buffer at the specified interval (which particularly useful when
              bigger  block  sizes  are used for a job). When set to 0, fio will use a chunk size
              that matches the block size resulting in a single random/fixed  region  within  the
              I/O  buffer. Defaults to 512. When the unit is omitted, the value is interpreted in
              bytes.

       buffer_pattern=str
              If set, fio will fill the I/O buffers with this pattern or with the contents  of  a
              file.  If  not  set,  the  contents of I/O buffers are defined by the other options
              related to buffer contents. The setting can be any pattern of  bytes,  and  can  be
              prefixed  with  0x  for  hex values. It may also be a string, where the string must
              then be wrapped with "". Or it may also be a filename, where the filename  must  be
              wrapped  with  ''  in which case the file is opened and read. Note that not all the
              file contents will be read if that would cause the buffers  to  overflow.  So,  for
              example:

                     buffer_pattern='filename'
                     or:
                     buffer_pattern="abcd"
                     or:
                     buffer_pattern=-12
                     or:
                     buffer_pattern=0xdeadface

              Also you can combine everything together in any order:

                     buffer_pattern=0xdeadface"abcd"-12'filename'

       dedupe_percentage=int
              If  set, fio will generate this percentage of identical buffers when writing. These
              buffers will be naturally dedupable. The contents of the  buffers  depend  on  what
              other  buffer  compression  settings  have  been  set.  It's  possible  to have the
              individual buffers either fully compressible, or not at all  --  this  option  only
              controls  the  distribution of unique buffers. Setting this option will also enable
              refill_buffers to prevent every buffer being identical.

       dedupe_mode=str
              If dedupe_percentage is given, then this option  controls  how  fio  generates  the
              dedupe buffers.

                     repeat

                            Generate dedupe buffers by repeating previous writes

                     working_set

                            Generate dedupe buffers from working set

              repeat  is  the  default  option for fio. Dedupe buffers are generated by repeating
              previous unique write.

              working_set    is    a    more    realistic    workload.      With     working_set,
              dedupe_working_set_percentage  should  be  provided.   Given that, fio will use the
              initial unique write buffers as its working set.  Upon deciding to dedupe, fio will
              randomly  choose a buffer from the working set.  Note that by using working_set the
              dedupe percentage will converge to the desired over time while repeat maintains the
              desired percentage throughout the job.

       dedupe_working_set_percentage=int
              If  dedupe_mode is set to working_set, then this controls the percentage of size of
              the file or device used as the buffers fio  will  choose  to  generate  the  dedupe
              buffers from

              Note that size needs to be explicitly provided and only 1 file per job is supported

       dedupe_global=bool
              This  controls  whether  the  deduplication buffers will be shared amongst all jobs
              that have this option set. The buffers  are  spread  evenly  between  participating
              jobs.

              Note  that dedupe_mode must be set to working_set for this to work.  Can be used in
              combination with compression

              invalidate=bool
                     Invalidate the buffer/page cache parts of the files  to  be  used  prior  to
                     starting  I/O  if  the  platform and file type support it. Defaults to true.
                     This will be ignored if pre_read is also specified for the same job.

              sync=str
                     Whether, and what type, of synchronous I/O to use for writes.   The  allowed
                     values are:

                            none   Do not use synchronous IO, the default.

                            0      Same as none.

                            sync   Use synchronous file IO. For the majority of I/O engines, this
                                   means using O_SYNC.

                            1      Same as sync.

                            dsync  Use synchronous data IO. For the majority of I/O engines, this
                                   means using O_DSYNC.

              iomem=str, mem=str
                     Fio  can  use  various  types  of memory as the I/O unit buffer. The allowed
                     values are:

                            malloc Use memory from malloc(3) as the buffers. Default memory type.

                            shm    Use shared memory as the buffers. Allocated through shmget(2).

                            shmhuge
                                   Same as shm, but use huge pages as backing.

                            mmap   Use mmap(2) to  allocate  buffers.  May  either  be  anonymous
                                   memory, or can be file backed if a filename is given after the
                                   option. The format is `mem=mmap:/path/to/file'.

                            mmaphuge
                                   Use a memory mapped huge file as the  buffer  backing.  Append
                                   filename after mmaphuge, ala `mem=mmaphuge:/hugetlbfs/file'.

                            mmapshared
                                   Same as mmap, but use a MMAP_SHARED mapping.

                            cudamalloc
                                   Use  GPU  memory  as the buffers for GPUDirect RDMA benchmark.
                                   The ioengine must be rdma.

                     The area allocated is a function of the maximum allowed bs size for the job,
                     multiplied  by  the  I/O  depth given. Note that for shmhuge and mmaphuge to
                     work, the system must have free huge pages allocated. This can  normally  be
                     checked  and  set  by reading/writing `/proc/sys/vm/nr_hugepages' on a Linux
                     system. Fio assumes a huge page is 2  or  4MiB  in  size  depending  on  the
                     platform.  So to calculate the number of huge pages you need for a given job
                     file, add up the I/O depth of all jobs (normally one unless iodepth is used)
                     and  multiply  by  the  maximum bs set.  Then divide that number by the huge
                     page size. You can see the size of the huge pages in `/proc/meminfo'. If  no
                     huge  pages  are  allocated  by  having a non-zero number in `nr_hugepages',
                     using mmaphuge or shmhuge will fail. Also see hugepage-size.

                     mmaphuge also needs to have hugetlbfs mounted and the file  location  should
                     point   there.   So   if   it's   mounted   in   `/huge',   you   would  use
                     `mem=mmaphuge:/huge/somefile'.

              iomem_align=int, mem_align=int
                     This indicates the memory alignment of the I/O memory buffers. Note that the
                     given  alignment  is  applied to the first I/O unit buffer, if using iodepth
                     the alignment of the following buffers are given by the bs  used.  In  other
                     words, if using a bs that is a multiple of the page sized in the system, all
                     buffers will be aligned to this value. If  using  a  bs  that  is  not  page
                     aligned,  the  alignment  of subsequent I/O memory buffers is the sum of the
                     iomem_align and bs used.

              hugepage-size=int
                     Defines the size of a huge page. Must  at  least  be  equal  to  the  system
                     setting,  see `/proc/meminfo' and `/sys/kernel/mm/hugepages/'. Defaults to 2
                     or 4MiB depending on the platform. Should probably always be a  multiple  of
                     megabytes,  so  using `hugepage-size=Xm' is the preferred way to set this to
                     avoid setting a non-pow-2 bad value.

              lockmem=int
                     Pin the specified amount of memory with mlock(2). Can be used to simulate  a
                     smaller amount of memory. The amount specified is per worker.

   I/O size
       size=int[%|z]
              The  total  size  of  file I/O for each thread of this job. Fio will run until this
              many bytes has been transferred, unless runtime is altered by other means  such  as
              (1)  runtime, (2) io_size, (3) number_ios, (4) gaps/holes while doing I/O's such as
              `rw=read:16K', or (5) sequential I/O reaching end of the  file  which  is  possible
              when  percentage_random  is  less  than 100.  Fio will divide this size between the
              available files determined by options such as nrfiles, filename, unless filesize is
              specified by the job. If the result of division happens to be 0, the size is set to
              the physical size of the given files or devices if they exist.  If this  option  is
              not  specified,  fio  will  use the full size of the given files or devices. If the
              files do not exist, size must be given. It is also  possible  to  give  size  as  a
              percentage  between 1 and 100. If `size=20%' is given, fio will use 20% of the full
              size of the given files or devices. In ZBD mode, size can  be  given  in  units  of
              number  of  zones using 'z'. Can be combined with offset to constrain the start and
              end range that I/O will be done within.

       io_size=int[%|z], io_limit=int[%|z]
              Normally fio operates within the region set by size,  which  means  that  the  size
              option  sets both the region and size of I/O to be performed. Sometimes that is not
              what you want. With this option, it is possible to define just the  amount  of  I/O
              that  fio  should  do.  For instance, if size is set to 20GiB and io_size is set to
              5GiB, fio will perform I/O within the first 20GiB but  exit  when  5GiB  have  been
              done.  The opposite is also possible -- if size is set to 20GiB, and io_size is set
              to 40GiB, then fio will do 40GiB of I/O within the 0..20GiB region.  Value  can  be
              set as percentage: io_size=N%.  In this case io_size multiplies size= value. In ZBD
              mode, value can also be set as number of zones using 'z'.

       filesize=irange(int)
              Individual file sizes. May be a range, in which case  fio  will  select  sizes  for
              files at random within the given range. If not given, each created file is the same
              size. This option overrides size in terms of file size, i.e.  size  becomes  merely
              the default for io_size (and has no effect it all if io_size is set explicitly).

       file_append=bool
              Perform I/O after the end of the file. Normally fio will operate within the size of
              a file. If this option is set, then fio will append to the file instead.  This  has
              identical  behavior to setting offset to the size of a file. This option is ignored
              on non-regular files.

       fill_device=bool, fill_fs=bool
              Sets size to something really large and waits for ENOSPC (no space left on  device)
              or EDQUOT (disk quota exceeded) as the terminating condition. Only makes sense with
              sequential write. For a read workload, the mount point will be  filled  first  then
              I/O started on the result.

   I/O engine
       ioengine=str
              Defines how the job issues I/O to the file. The following types are defined:

                     sync   Basic  read(2)  or write(2) I/O. lseek(2) is used to position the I/O
                            location.  See fsync and fdatasync for syncing write I/Os.

                     psync  Basic pread(2) or pwrite(2) I/O. Default on all  supported  operating
                            systems except for Windows.

                     vsync  Basic  readv(2)  or writev(2) I/O. Will emulate queuing by coalescing
                            adjacent I/Os into a single submission.

                     pvsync Basic preadv(2) or pwritev(2) I/O.

                     pvsync2
                            Basic preadv2(2) or pwritev2(2) I/O.

                     io_uring
                            Fast Linux native asynchronous I/O. Supports async IO for both direct
                            and buffered IO.  This engine defines engine specific options.

                     io_uring_cmd
                            Fast  Linux  native  asynchronous I/O for passthrough commands.  This
                            engine defines engine specific options.

                     libaio Linux native asynchronous I/O.  Note  that  Linux  may  only  support
                            queued   behavior   with   non-buffered   I/O   (set   `direct=1'  or
                            `buffered=0').  This engine defines engine specific options.

                     posixaio
                            POSIX asynchronous I/O using aio_read(3) and aio_write(3).

                     solarisaio
                            Solaris native asynchronous I/O.

                     windowsaio
                            Windows native asynchronous I/O. Default on Windows.

                     mmap   File is memory mapped with mmap(2)  and  data  copied  to/from  using
                            memcpy(3).

                     splice splice(2)  is  used  to transfer the data and vmsplice(2) to transfer
                            data from user space to the kernel.

                     sg     SCSI generic sg v3 I/O. May either be  synchronous  using  the  SG_IO
                            ioctl,  or if the target is an sg character device we use read(2) and
                            write(2) for asynchronous I/O. Requires filename  option  to  specify
                            either   block  or  character  devices.  This  engine  supports  trim
                            operations. The sg engine includes engine specific options.

                     libzbc Read, write, trim and ZBC/ZAC operations  to  a  zoned  block  device
                            using libzbc library. The target can be either an SG character device
                            or a block device file.

                     null   Doesn't transfer any data, just pretends to. This is mainly  used  to
                            exercise fio itself and for debugging/testing purposes.

                     net    Transfer  over  the  network  to  given `host:port'. Depending on the
                            protocol used, the hostname, port, listen and  filename  options  are
                            used  to  specify what sort of connection to make, while the protocol
                            option determines which protocol will be used.  This  engine  defines
                            engine specific options.

                     netsplice
                            Like  net,  but  uses  splice(2)  and  vmsplice(2)  to  map  data and
                            send/receive.  This engine defines engine specific options.

                     cpuio  Doesn't transfer any data, but burns  CPU  cycles  according  to  the
                            cpuload,  cpuchunks and cpumode options.  A job never finishes unless
                            there is at least one non-cpuio job.

                            cpuload=85 will cause that job to do nothing but burn 85% of the CPU.
                            In  case  of SMP machines, use numjobs=<nr_of_cpu> to get desired CPU
                            usage, as the cpuload only loads a single CPU at the desired rate.

                            cpumode=qsort replace the default noop instructions loop by  a  qsort
                            algorithm to consume more energy.

                     rdma   The   RDMA   I/O   engine   supports   both   RDMA  memory  semantics
                            (RDMA_WRITE/RDMA_READ) and  channel  semantics  (Send/Recv)  for  the
                            InfiniBand,  RoCE  and  iWARP  protocols.  This engine defines engine
                            specific options.
                     falloc I/O engine that does regular fallocate to simulate data  transfer  as
                            fio ioengine.
                            DDIR_READ      does fallocate(,mode = FALLOC_FL_KEEP_SIZE,).
                            DIR_WRITE      does fallocate(,mode = 0).
                            DDIR_TRIM                 does            fallocate(,mode           =
                            FALLOC_FL_KEEP_SIZE|FALLOC_FL_PUNCH_HOLE).

                     ftruncate
                            I/O engine that sends ftruncate(2) operations in  response  to  write
                            (DDIR_WRITE)  events.  Each  ftruncate issued sets the file's size to
                            the current block offset. blocksize is ignored.

                     e4defrag
                            I/O engine that does regular  EXT4_IOC_MOVE_EXT  ioctls  to  simulate
                            defragment activity in request to DDIR_WRITE event.

                     rados  I/O  engine  supporting  direct  access  to  Ceph  Reliable Autonomic
                            Distributed Object Store (RADOS) via librados. This ioengine  defines
                            engine specific options.

                     rbd    I/O engine supporting direct access to Ceph Rados Block Devices (RBD)
                            via librbd without the need  to  use  the  kernel  rbd  driver.  This
                            ioengine defines engine specific options.

                     http   I/O engine supporting GET/PUT requests over HTTP(S) with libcurl to a
                            WebDAV  or  S3  endpoint.   This  ioengine  defines  engine  specific
                            options.

                            This  engine  only supports direct IO of iodepth=1; you need to scale
                            this via numjobs. blocksize defines the size of  the  objects  to  be
                            created.

                            TRIM is translated to object deletion.

                     gfapi  Using GlusterFS libgfapi sync interface to direct access to GlusterFS
                            volumes without having to go  through  FUSE.  This  ioengine  defines
                            engine specific options.

                     gfapi_async
                            Using   GlusterFS  libgfapi  async  interface  to  direct  access  to
                            GlusterFS volumes without having to go through  FUSE.  This  ioengine
                            defines engine specific options.

                     libhdfs
                            Read  and write through Hadoop (HDFS). The filename option is used to
                            specify host,port of the  hdfs  name-node  to  connect.  This  engine
                            interprets  offsets a little differently. In HDFS, files once created
                            cannot be modified so random writes are not possible. To imitate this
                            the  libhdfs engine expects a bunch of small files to be created over
                            HDFS and will randomly pick a file from  them  based  on  the  offset
                            generated  by  fio  backend  (see the example job file to create such
                            files, use `rw=write' option). Please note, it may  be  necessary  to
                            set  environment  variables  to work with HDFS/libhdfs properly. Each
                            job uses its own connection to HDFS.

                     mtd    Read, write and erase an MTD character  device  (e.g.,  `/dev/mtd0').
                            Discards  are  treated  as erases. Depending on the underlying device
                            type, the I/O may have to go in a certain  pattern,  e.g.,  on  NAND,
                            writing   sequentially   to   erase   blocks  and  discarding  before
                            overwriting. The trimwrite mode works well for this constraint.

                     dev-dax
                            Read and write using device DAX to a persistent memory device  (e.g.,
                            /dev/dax0.0) through the PMDK libpmem library.

                     external
                            Prefix  to specify loading an external I/O engine object file. Append
                            the engine  filename,  e.g.  `ioengine=external:/tmp/foo.o'  to  load
                            ioengine  `foo.o'  in  `/tmp'.  The  path  can  be either absolute or
                            relative. See `engines/skeleton_external.c' in  the  fio  source  for
                            details of writing an external I/O engine.

                     filecreate
                            Simply create the files and do no I/O to them.  You still need to set
                            filesize so that all the accounting still occurs, but no  actual  I/O
                            will be done other than creating the file.

                     filestat
                            Simply  do  stat()  and  do  no  I/O  to  the  file.  You need to set
                            'filesize' and 'nrfiles', so that files will be created.  This engine
                            is to measure file lookup and meta data access.

                     filedelete
                            Simply  delete  files by unlink() and do no I/O to the file. You need
                            to set 'filesize' and 'nrfiles', so that files will be created.  This
                            engine is to measure file delete.

                     libpmem
                            Read  and write using mmap I/O to a file on a filesystem mounted with
                            DAX on a persistent memory device through the PMDK libpmem library.

                     ime_psync
                            Synchronous read and write using DDN's Infinite Memory Engine  (IME).
                            This  engine  is very basic and issues calls to IME whenever an IO is
                            queued.

                     ime_psyncv
                            Synchronous read and write using DDN's Infinite Memory Engine  (IME).
                            This engine uses iovecs and will try to stack as much IOs as possible
                            (if the IOs are "contiguous" and the IO depth is not exceeded) before
                            issuing a call to IME.

                     ime_aio
                            Asynchronous read and write using DDN's Infinite Memory Engine (IME).
                            This engine will try to stack as much IOs  as  possible  by  creating
                            requests  for  IME.   FIO  will  then  decide  when  to  commit these
                            requests.

                     libiscsi
                            Read and write iscsi lun with libiscsi.

                     nbd    Synchronous read and write a Network Block Device (NBD).

                     libcufile
                            I/O engine supporting libcufile synchronous access to nvidia-fs and a
                            GPUDirect  Storage-supported  filesystem.  This  engine  performs I/O
                            without transferring  buffers  between  user-space  and  the  kernel,
                            unless  verify  is  set  or  cuda_io  is  posix.  iomem  must  not be
                            cudamalloc. This ioengine defines engine specific options.

                     dfs    I/O engine supporting asynchronous read and write operations  to  the
                            DAOS File System (DFS) via libdfs.

                     nfs    I/O  engine  supporting asynchronous read and write operations to NFS
                            filesystems from userspace via libnfs. This is useful  for  achieving
                            higher  concurrency  and  thus throughput than is possible via kernel
                            NFS.

                     exec   Execute 3rd party tools. Could be used to perform  monitoring  during
                            jobs runtime.

                     xnvme  I/O  engine using the xNVMe C API, for NVMe devices. The xnvme engine
                            provides flexibility to  access  GNU/Linux  Kernel  NVMe  driver  via
                            libaio,  IOCTLs,  io_uring,  the SPDK NVMe driver, or your own custom
                            NVMe driver. The xnvme engine includes engine specific options.  (See
                            https://xnvme.io/).

                     libblkio
                            Use  the libblkio library (https://gitlab.com/libblkio/libblkio). The
                            specific  driver  to  use  must  be  set  using  libblkio_driver.  If
                            mem/iomem  is  not  specified,  memory  allocation  is  delegated  to
                            libblkio (and so is guaranteed to work with the selected driver). One
                            libblkio  instance  is  used  per process, so all jobs setting option
                            thread will share a single instance (with one queue per  thread)  and
                            must  specify  compatible options. Note that some drivers don't allow
                            several instances to access the same device or  file  simultaneously,
                            but allow it for threads.

   I/O engine specific parameters
       In addition, there are some parameters which are only valid when a specific ioengine is in
       use. These are used identically to normal parameters, with the caveat that  when  used  on
       the command line, they must come after the ioengine that defines them is selected.

       (io_uring,libaio)cmdprio_percentage=int[,int]
              Set  the percentage of I/O that will be issued with the highest priority.  Default:
              0. A single value applies to  reads  and  writes.  Comma-separated  values  may  be
              specified  for reads and writes. For this option to be effective, NCQ priority must
              be supported and enabled, and `direct=1' option must be used. fio must also be  run
              as  the  root  user.  Unlike slat/clat/lat stats, which can be tracked and reported
              independently, per priority stats only track and report a single type  of  latency.
              By  default, completion latency (clat) will be reported, if lat_percentiles is set,
              total latency (lat) will be reported.

       (io_uring,libaio)cmdprio_class=int[,int]
              Set the I/O priority class to use for I/Os that must be issued with a priority when
              cmdprio_percentage   or   cmdprio_bssplit   is   set.    If   not   specified  when
              cmdprio_percentage or cmdprio_bssplit is set, this defaults to the highest priority
              class.  A  single  value applies to reads and writes. Comma-separated values may be
              specified for reads and writes. See man ionice(1). See also the prioclass option.

       (io_uring,libaio)cmdprio=int[,int]
              Set the I/O priority value to use for I/Os that must be issued with a priority when
              cmdprio_percentage   or   cmdprio_bssplit   is   set.    If   not   specified  when
              cmdprio_percentage or cmdprio_bssplit is set, this defaults to 0. Linux  limits  us
              to  a  positive  value  between  0  and 7, with 0 being the highest. A single value
              applies to reads and writes.  Comma-separated values may be specified for reads and
              writes.  See  man  ionice(1).  Refer  to an appropriate manpage for other operating
              systems since the meaning of priority may differ. See also the prio option.

       (io_uring,libaio)cmdprio_bssplit=str[,str]
              To get a finer control  over  I/O  priority,  this  option  allows  specifying  the
              percentage  of IOs that must have a priority set depending on the block size of the
              IO. This option is useful only when used together with the option bssplit, that is,
              multiple different block sizes are used for reads and writes.

              The  first accepted format for this option is the same as the format of the bssplit
              option:

                     cmdprio_bssplit=blocksize/percentage:blocksize/percentage

              In this case, each entry will use the priority class and priority level defined  by
              the options cmdprio_class and cmdprio respectively.

              The second accepted format for this option is:

                     cmdprio_bssplit=blocksize/percentage/class/level:blocksize/percentage/class/level

              In this case, the priority class and priority level is defined inside  each  entry.
              In  comparison  with the first accepted format, the second accepted format does not
              restrict all entries to have the same priority class and priority level.

              For both formats, only the read and write data directions are supported, values for
              trim IOs are ignored. This option is mutually exclusive with the cmdprio_percentage
              option.

       (io_uring,io_uring_cmd)fixedbufs
              If fio is asked to do direct IO, then Linux will map pages for each  IO  call,  and
              release  them  when  IO  is  done.  If this option is set, the pages are pre-mapped
              before IO is started. This eliminates the need to map  and  release  for  each  IO.
              This is more efficient, and reduces the IO latency as well.

       (io_uring,io_uring_cmd)nonvectored=int
              With this option, fio will use non-vectored read/write commands, where address must
              contain the address directly. Default is -1.

       (io_uring,io_uring_cmd)force_async
              Normal operation for io_uring is to try and issue an sqe as non-blocking first, and
              if that fails, execute it in an async manner. With this option set to N, then every
              N request fio will ask sqe to be issued in an async manner. Default is 0.

       (io_uring,io_uring_cmd,xnvme)hipri
              If this option is set, fio will attempt to use polled  IO  completions.  Normal  IO
              completions  generate interrupts to signal the completion of IO, polled completions
              do not. Hence they are require active reaping by the application.  The benefits are
              more  efficient IO for high IOPS scenarios, and lower latencies for low queue depth
              IO.

       (io_uring,io_uring_cmd)registerfiles
              With this option, fio registers the set of files being used with the kernel.   This
              avoids  the  overhead  of managing file counts in the kernel, making the submission
              and completion part more lightweight. Required for the below sqthread_poll option.

       (io_uring,io_uring_cmd,xnvme)sqthread_poll
              Normally fio will submit IO by issuing a  system  call  to  notify  the  kernel  of
              available  items  in  the  SQ ring. If this option is set, the act of submitting IO
              will be done by a polling thread in the kernel. This frees up cycles  for  fio,  at
              the  cost  of using more CPU in the system. As submission is just the time it takes
              to fill in the sqe entries and any syscall required to  wake  up  the  idle  kernel
              thread, fio will not report submission latencies.

       (io_uring,io_uring_cmd)sqthread_poll_cpu=int
              When  `sqthread_poll` is set, this option provides a way to define which CPU should
              be used for the polling thread.

       (io_uring_cmd)cmd_type=str
              Specifies the type of uring passthrough command to  be  used.  Supported  value  is
              nvme. Default is nvme.

       (libaio)userspace_reap
              Normally,  with  the  libaio engine in use, fio will use the io_getevents(3) system
              call to reap newly returned events. With this flag turned on, the AIO ring will  be
              read directly from user-space to reap events. The reaping mode is only enabled when
              polling for a minimum of 0 events (e.g. when `iodepth_batch_complete=0').

       (pvsync2)hipri
              Set RWF_HIPRI on I/O, indicating to the kernel that it's of  higher  priority  than
              normal.

       (pvsync2)hipri_percentage
              When  hipri  is  set  this  determines  the probability of a pvsync2 I/O being high
              priority. The default is 100%.

       (pvsync2,libaio,io_uring,io_uring_cmd)nowait=bool
              By default if a request cannot be executed immediately (e.g.  resource  starvation,
              waiting on locks) it is queued and the initiating process will be blocked until the
              required resource becomes free.  This option sets the  RWF_NOWAIT  flag  (supported
              from  the  4.14  Linux  kernel) and the call will return instantly with EAGAIN or a
              partial result rather than waiting.

              It is useful to also use ignore_error=EAGAIN when using this option.   Note:  glibc
              2.27, 2.28 have a bug in syscall wrappers preadv2, pwritev2.  They return EOPNOTSUP
              instead of EAGAIN.

              For cached I/O, using this option usually means a request operates only with cached
              data.  Currently  the  RWF_NOWAIT  flag  does  not supported for cached write.  For
              direct I/O, requests will only succeed if cache invalidation isn't  required,  file
              blocks are fully allocated and the disk request could be issued immediately.

       (io_uring_cmd)fdp=bool
              Enable Flexible Data Placement mode for write commands.

       (io_uring_cmd)fdp_pli=str
              Select which Placement ID Index/Indicies this job is allowed to use for writes.  By
              default, the job will cycle through all available Placement IDs,  so  use  this  to
              isolate  these  identifiers  to  specific  jobs.  If  you want fio to use placement
              identifier only at indices 0, 2 and 5 specify, you would set `fdp_pli=0,2,5`.

       (cpuio)cpuload=int
              Attempt to use the specified percentage of CPU cycles. This is a  mandatory  option
              when using cpuio I/O engine.

       (cpuio)cpuchunks=int
              Split the load into cycles of the given time. In microseconds.

       (cpuio)cpumode=str
              Specify how to stress the CPU. It can take these two values:

                     noop   This is the default and directs the CPU to execute noop instructions.

                     qsort  Replace  the  default  noop  instructions  with  a qsort algorithm to
                            consume more energy.

       (cpuio)exit_on_io_done=bool
              Detect when I/O threads are done, then exit.

       (libhdfs)namenode=str
              The hostname or IP address of a HDFS cluster namenode to contact.

       (libhdfs)port=int
              The listening port of the HFDS cluster namenode.

       (netsplice,net)port=int
              The TCP or UDP port to bind to or connect to. If this is used with numjobs to spawn
              multiple instances of the same job type, then this will be the starting port number
              since fio will use a range of ports.

       (rdma,librpma_*)port=int
              The port to use for RDMA-CM communication. This should be the  same  value  on  the
              client and the server side.

       (netsplice,net,rdma)hostname=str
              The hostname or IP address to use for TCP, UDP or RDMA-CM based I/O.  If the job is
              a TCP listener or UDP reader, the hostname is not used and must be  omitted  unless
              it is a valid UDP multicast address.

       (librpma_*)serverip=str
              The IP address to be used for RDMA-CM based I/O.

       (librpma_*_server)direct_write_to_pmem=bool
              Set  to  1  only  when  Direct  Write  to  PMem  from  the remote host is possible.
              Otherwise, set to 0.

       (librpma_*_server)busy_wait_polling=bool
              Set to 0 to wait for completion instead of busy-wait polling completion.   Default:
              1.

       (netsplice,net)interface=str
              The IP address of the network interface used to send or receive UDP multicast.

       (netsplice,net)ttl=int
              Time-to-live value for outgoing UDP multicast packets. Default: 1.

       (netsplice,net)nodelay=bool
              Set TCP_NODELAY on TCP connections.

       (netsplice,net)protocol=str, proto=str
              The network protocol to use. Accepted values are:

                     tcp    Transmission control protocol.

                     tcpv6  Transmission control protocol V6.

                     udp    User datagram protocol.

                     udpv6  User datagram protocol V6.

                     unix   UNIX domain socket.

              When  the  protocol  is  TCP  or  UDP,  the port must also be given, as well as the
              hostname if the job is a TCP listener or UDP reader. For unix sockets,  the  normal
              filename option should be used and the port is invalid.

       (netsplice,net)listen
              For  TCP  network  connections,  tell fio to listen for incoming connections rather
              than initiating an outgoing connection. The hostname must be omitted if this option
              is used.

       (netsplice,net)pingpong
              Normally  a  network  writer  will just continue writing data, and a network reader
              will just consume packages. If `pingpong=1' is set, a writer will send  its  normal
              payload to the reader, then wait for the reader to send the same payload back. This
              allows fio to measure network latencies. The submission  and  completion  latencies
              then  measure  local  time  spent  sending or receiving, and the completion latency
              measures how long it took for the other end to  receive  and  send  back.  For  UDP
              multicast traffic `pingpong=1' should only be set for a single reader when multiple
              readers are listening to the same address.

       (netsplice,net)window_size=int
              Set the desired socket buffer size for the connection.

       (netsplice,net)mss=int
              Set the TCP maximum segment size (TCP_MAXSEG).

       (e4defrag)donorname=str
              File will be used as a block donor (swap extents between files).

       (e4defrag)inplace=int
              Configure donor file blocks allocation strategy:

                     0      Default. Preallocate donor's file on init.

                     1      Allocate space immediately inside defragment event,  and  free  right
                            after event.

       (rbd,rados)clustername=str
              Specifies the name of the Ceph cluster.

       (rbd)rbdname=str
              Specifies the name of the RBD.

       (rbd,rados)pool=str
              Specifies the name of the Ceph pool containing RBD or RADOS data.

       (rbd,rados)clientname=str
              Specifies  the  username  (without  the  'client.'  prefix) used to access the Ceph
              cluster. If the  clustername  is  specified,  the  clientname  shall  be  the  full
              *type.id* string. If no type. prefix is given, fio will add 'client.'  by default.

       (rados)conf=str
              Specifies  the configuration path of ceph cluster, so conf file does not have to be
              /etc/ceph/ceph.conf.

       (rbd,rados)busy_poll=bool
              Poll store  instead  of  waiting  for  completion.  Usually  this  provides  better
              throughput at cost of higher(up to 100%) CPU utilization.

       (rados)touch_objects=bool
              During  initialization,  touch  (create  if  do  not  exist)  all  objects (files).
              Touching all objects affects ceph caches and likely impacts test results.   Enabled
              by default.

       (http)http_host=str
              Hostname to connect to. For S3, this could be the bucket name. Default is localhost

       (http)http_user=str
              Username for HTTP authentication.

       (http)http_pass=str
              Password for HTTP authentication.

       (http)https=str
              Whether  to use HTTPS instead of plain HTTP. on enables HTTPS; insecure will enable
              HTTPS, but disable SSL peer verification (use with caution!).  Default is off.

       (http)http_mode=str
              Which HTTP access mode to use: webdav, swift, or s3. Default is webdav.

       (http)http_s3_region=str
              The S3 region/zone to include in the request. Default is us-east-1.

       (http)http_s3_key=str
              The S3 secret key.

       (http)http_s3_keyid=str
              The S3 key/access id.

       (http)http_s3_sse_customer_key=str
              The encryption customer key in SSE server side.

       (http)http_s3_sse_customer_algorithm=str
              The encryption customer algorithm in SSE server side. Default is AES256

       (http)http_s3_storage_class=str
              Which storage class to access. User-customizable settings. Default is STANDARD

       (http)http_swift_auth_token=str
              The Swift auth token. See the example configuration file on how to retrieve this.

       (http)http_verbose=int
              Enable verbose requests from libcurl. Useful for  debugging.  1  turns  on  verbose
              logging from libcurl, 2 additionally enables HTTP IO tracing.  Default is 0

       (mtd)skip_bad=bool
              Skip operations against known bad blocks.

       (libhdfs)hdfsdirectory
              libhdfs will create chunk in this HDFS directory.

       (libhdfs)chunk_size
              The size of the chunk to use for each file.

       (rdma)verb=str
              The RDMA verb to use on this side of the RDMA ioengine connection. Valid values are
              write, read, send and recv. These correspond to the  equivalent  RDMA  verbs  (e.g.
              write  =  rdma_write etc.). Note that this only needs to be specified on the client
              side of the connection. See the examples folder.

       (rdma)bindname=str
              The name to use to bind the local RDMA-CM connection to a local RDMA  device.  This
              could  be  a  hostname  or an IPv4 or IPv6 address. On the server side this will be
              passed into the rdma_bind_addr() function and on the client site it will be used in
              the  rdma_resolve_add()  function.  This  can  be  useful when multiple paths exist
              between the client and the server or in certain loopback configurations.

       (filestat)stat_type=str
              Specify stat system call type to measure lookup/getattr  performance.   Default  is
              stat for stat(2).

       (sg)hipri
              If  this  option  is  set, fio will attempt to use polled IO completions. This will
              have a similar effect as (io_uring)hipri. Only SCSI READ and  WRITE  commands  will
              have  the SGV4_FLAG_HIPRI set (not UNMAP (trim) nor VERIFY).  Older versions of the
              Linux sg driver that do not support hipri will  simply  ignore  this  flag  and  do
              normal  IO. The Linux SCSI Low Level Driver (LLD) that "owns" the device also needs
              to support hipri (also known as iopoll and mq_poll).  The  MegaRAID  driver  is  an
              example  of  a  SCSI LLD.  Default: clear (0) which does normal (interrupted based)
              IO.

       (sg)readfua=bool
              With readfua option set to 1, read operations include the force unit  access  (fua)
              flag. Default: 0.

       (sg)writefua=bool
              With writefua option set to 1, write operations include the force unit access (fua)
              flag. Default: 0.

       (sg)sg_write_mode=str
              Specify the type of write commands to issue. This option can take multiple values:

                     write (default)
                            Write opcodes are issued as usual

                     write_and_verify
                            Issue WRITE AND VERIFY commands. The BYTCHK bit is set to  00b.  This
                            directs  the  device  to carry out a medium verification with no data
                            comparison for the data that was  written.  The  writefua  option  is
                            ignored with this selection.

                     verify This option is deprecated. Use write_and_verify instead.

                     write_same
                            Issue  WRITE  SAME  commands.  This  transfers  a single block to the
                            device and writes this same block of data to a contiguous sequence of
                            LBAs  beginning  at  the specified offset. fio's block size parameter
                            specifies the amount of data written with each command. However,  the
                            amount  of  data  actually  transferred to the device is equal to the
                            device's block (sector) size. For a device  with  512  byte  sectors,
                            blocksize=8k  will write 16 sectors with each command. fio will still
                            generate 8k of data for each command butonly the first 512 bytes will
                            be used and transferred to the device. The writefua option is ignored
                            with this selection.

                     same   This option is deprecated. Use write_same instead.

                     write_same_ndob
                            Issue WRITE SAME(16) commands as above but with the  No  Data  Output
                            Buffer (NDOB) bit set. No data will be transferred to the device with
                            this bit set. Data written will be a pre-determined pattern  such  as
                            all zeroes.

                     write_stream
                            Issue  WRITE STREAM(16) commands. Use the stream_id option to specify
                            the stream identifier.

                     verify_bytchk_00
                            Issue VERIFY commands with BYTCHK set to 00. This directs the  device
                            to carry out a medium verification with no data comparison.

                     verify_bytchk_01
                            Issue  VERIFY commands with BYTCHK set to 01. This directs the device
                            to compare the data on the device with the data  transferred  to  the
                            device.

                     verify_bytchk_11
                            Issue  VERIFY commands with BYTCHK set to 11. This transfers a single
                            block to the device and compares the contents of this block with  the
                            data  on  the  device  beginning at the specified offset. fio's block
                            size parameter specifies the total amount of data compared with  this
                            command.   However,   only  one  block  (sector)  worth  of  data  is
                            transferred to the device. This is similar to the WRITE SAME  command
                            except that data is compared instead of written.

       (sg)stream_id=int
              Set  the stream identifier for WRITE STREAM commands. If this is set to 0 (which is
              not a valid stream identifier) fio will open a stream and then close it when  done.
              Default is 0.

       (nbd)uri=str
              Specify  the  NBD URI of the server to test.  The string is a standard NBD URI (see
              https://github.com/NetworkBlockDevice/nbd/tree/master/doc).  Example URIs:

                     nbd://localhost:10809

                     nbd+unix:///?socket=/tmp/socket

                     nbds://tlshost/exportname

       (libcufile)gpu_dev_ids=str
              Specify the GPU IDs to use with CUDA. This is a colon-separated list of int.   GPUs
              are assigned to workers roundrobin. Default is 0.

       (libcufile)cuda_io=str
              Specify the type of I/O to use with CUDA. This option takes the following values:

                     cufile (default)
                            Use  libcufile  and  nvidia-fs.  This  option  performs  I/O directly
                            between a GPUDirect Storage filesystem and GPU buffers, avoiding  use
                            of  a  bounce  buffer.  If  verify is set, cudaMemcpy is used to copy
                            verification data between  RAM  and  GPU(s).   Verification  data  is
                            copied  from  RAM  to  GPU before a write and from GPU to RAM after a
                            read.  direct must be 1.

                     posix  Use POSIX to perform I/O with a RAM buffer,  and  use  cudaMemcpy  to
                            transfer data between RAM and the GPU(s).  Data is copied from GPU to
                            RAM before a write and copied from RAM to GPU after  a  read.  verify
                            does not affect the use of cudaMemcpy.

       (dfs)pool
              Specify the label or UUID of the DAOS pool to connect to.

       (dfs)cont
              Specify the label or UUID of the DAOS container to open.

       (dfs)chunk_size
              Specify  a  different chunk size (in bytes) for the dfs file.  Use DAOS container's
              chunk size by default.

       (dfs)object_class
              Specify a different object class for the dfs file.   Use  DAOS  container's  object
              class by default.

       (nfs)nfs_url
              URL  in  libnfs format, eg nfs://<server|ipv4|ipv6>/path[?arg=val[&arg=val]*] Refer
              to the libnfs README for more details.

       (exec)program=str
              Specify the program to execute.  Note the program will receive a SIGTERM  when  the
              job  is reaching the time limit.  A SIGKILL is sent once the job is over. The delay
              between the two signals is defined by grace_time option.

       (exec)arguments=str
              Specify arguments to pass to program.  Some special variables can  be  expanded  to
              pass fio's job details to the program :

                     %r     replaced by the duration of the job in seconds

                     %n     replaced by the name of the job

       (exec)grace_time=int
              Defines the time between the SIGTERM and SIGKILL signals. Default is 1 second.

       (exec)std_redirect=bool
              If  set, stdout and stderr streams are redirected to files named from the job name.
              Default is true.

       (xnvme)xnvme_async=str
              Select the xnvme async command interface. This can take these values.

                     emu    This is default and use to emulate asynchronous I/O by using a single
                            thread  to  create a queue pair on top of a synchronous I/O interface
                            using the NVMe driver IOCTL.

                     thrpool
                            Emulate an asynchronous  I/O  interface  with  a  pool  of  userspace
                            threads  on  top of a synchronous I/O interface using the NVMe driver
                            IOCTL. By default four threads are used.

                     io_uring
                            Linux native asynchronous I/O interface which  supports  both  direct
                            and buffered I/O.

                     libaio Use Linux aio for Asynchronous I/O

                     posix  Use  the  posix asynchronous I/O interface to perform one or more I/O
                            operations asynchronously.

                     vfio   Use the  user-space  VFIO-based  backend,  implemented  using  libvfn
                            instead of SPDK.

                     nil    Do  not  transfer  any data; just pretend to. This is mainly used for
                            introspective performance evaluation.

       (xnvme)xnvme_sync=str
              Select the xnvme synchronous command interface. This can take these values.

                     nvme   This is default and uses Linux NVMe Driver  ioctl()  for  synchronous
                            I/O.

                     psync  This  supports  regular  as  well  as  vectored  pread() and pwrite()
                            commands.

                     block  This is  the  same  as  psync  except  that  it  also  supports  zone
                            management commands using Linux block layer IOCTLs.

       (xnvme)xnvme_admin=str
              Select the xnvme admin command interface. This can take these values.

                     nvme   This  is  default  and  uses  Linux  NVMe  Driver  ioctl()  for admin
                            commands.

                     block  Use Linux Block Layer ioctl() and sysfs for admin commands.

       (xnvme)xnvme_dev_nsid=int
              xnvme namespace identifier for userspace NVMe driver SPDK or vfio.

       (xnvme)xnvme_dev_subnqn=str
              Sets the subsystem NQN for fabrics. This is for xNVMe to utilize a  fabrics  target
              with multiple systems.

       (xnvme)xnvme_mem=str
              Select the xnvme memory backend. This can take these values.

                     posix  This is the default posix memory backend for linux NVMe driver.

                     hugepage
                            Use  hugepages,  instead of existing posix memory backend. The memory
                            backend uses hugetlbfs. This require  users  to  allocate  hugepages,
                            mount    hugetlbfs    and    set    an   enviornment   variable   for
                            XNVME_HUGETLB_PATH.

                     spdk   Uses SPDK's memory allocator.

                     vfio   Uses libvfn's memory allocator. This also specifies the use of libvfn
                            backend instead of SPDK.

       (xnvme)xnvme_iovec
              If this option is set, xnvme will use vectored read/write commands.

       (libblkio)libblkio_driver=str
              The  libblkio  driver  to  use.  Different drivers access devices through different
              underlying interfaces. Available drivers depend on the libblkio version in use  and
              are listed at https://libblkio.gitlab.io/libblkio/blkio.html#drivers

       (libblkio)libblkio_path=str
              Sets  the  value  of  the  driver-specific  "path"  property  before connecting the
              libblkio instance, which identifies the target device or file on which  to  perform
              I/O.  Its  exact semantics are driver-dependent and not all drivers may support it;
              see https://libblkio.gitlab.io/libblkio/blkio.html#drivers

       (libblkio)libblkio_pre_connect_props=str
              A colon-separated list of additional libblkio properties to be set  after  creating
              but  before  connecting  the  libblkio instance. Each property must have the format
              <name>=<value>. Colons can be escaped as \:. These are set after  the  engine  sets
              any  other  properties,  so those can be overriden.  Available properties depend on
              the     libblkio     version      in      use      and      are      listed      at
              https://libblkio.gitlab.io/libblkio/blkio.html#properties

       (libblkio)libblkio_num_entries=int
              Sets  the  value  of the driver-specific "num-entries" property before starting the
              libblkio instance. Its exact semantics are driver-dependent and not all drivers may
              support it; see https://libblkio.gitlab.io/libblkio/blkio.html#drivers

       (libblkio)libblkio_queue_size=int
              Sets  the  value  of  the driver-specific "queue-size" property before starting the
              libblkio instance. Its exact semantics are driver-dependent and not all drivers may
              support it; see https://libblkio.gitlab.io/libblkio/blkio.html#drivers

       (libblkio)libblkio_pre_start_props=str
              A colon-separated list of additional libblkio properties to be set after connecting
              but before starting the libblkio instance.  Each  property  must  have  the  format
              <name>=<value>.  Colons  can  be escaped as \:. These are set after the engine sets
              any other properties, so those can be overriden.  Available  properties  depend  on
              the      libblkio      version      in      use      and      are     listed     at
              https://libblkio.gitlab.io/libblkio/blkio.html#properties

       (libblkio)hipri
              Use  poll  queues.  This  is  incompatible  with   libblkio_wait_mode=eventfd   and
              libblkio_force_enable_completion_eventfd.

       (libblkio)libblkio_vectored
              Submit vectored read and write requests.

       (libblkio)libblkio_write_zeroes_on_trim
              Submit trims as "write zeroes" requests instead of discard requests.

       (libblkio)libblkio_wait_mode=str
              How to wait for completions:

                     block (default)
                            Use a blocking call to blkioq_do_io().

                     eventfd
                            Use a blocking call to read() on the completion eventfd.

                     loop   Use a busy loop with a non-blocking call to blkioq_do_io().

       (libblkio)libblkio_force_enable_completion_eventfd
              Enable   the   queue's  completion  eventfd  even  when  unused.  This  may  impact
              performance. The default is to enable it only if libblkio_wait_mode=eventfd.

       (windowsaio)no_completion_thread
              Avoid using a separate thread for completion polling.

   I/O depth
       iodepth=int
              Number of I/O units to keep in  flight  against  the  file.  Note  that  increasing
              iodepth  beyond  1  will not affect synchronous ioengines (except for small degrees
              when verify_async is in use). Even async engines may impose OS restrictions causing
              the  desired  depth  not to be achieved. This may happen on Linux when using libaio
              and not setting `direct=1', since buffered I/O is not async on that OS. Keep an eye
              on  the  I/O depth distribution in the fio output to verify that the achieved depth
              is as expected. Default: 1.

       iodepth_batch_submit=int, iodepth_batch=int
              This defines how many pieces of I/O to submit at once. It defaults to 1 which means
              that  we  submit  each  I/O as soon as it is available, but can be raised to submit
              bigger batches of I/O at the time. If it is set to 0  the  iodepth  value  will  be
              used.

       iodepth_batch_complete_min=int, iodepth_batch_complete=int
              This  defines  how  many  pieces of I/O to retrieve at once. It defaults to 1 which
              means that we'll ask for a minimum of 1 I/O  in  the  retrieval  process  from  the
              kernel.  The I/O retrieval will go on until we hit the limit set by iodepth_low. If
              this variable is set to 0, then fio will always check for completed  events  before
              queuing  more  I/O.  This  helps  reduce I/O latency, at the cost of more retrieval
              system calls.

       iodepth_batch_complete_max=int
              This defines maximum pieces of I/O to retrieve at once.  This  variable  should  be
              used  along  with  iodepth_batch_complete_min=int variable, specifying the range of
              min and max amount of I/O which should be retrieved. By  default  it  is  equal  to
              iodepth_batch_complete_min value. Example #1:

                     iodepth_batch_complete_min=1
                     iodepth_batch_complete_max=<iodepth>

              which  means  that  we  will  retrieve at least 1 I/O and up to the whole submitted
              queue depth. If none of I/O has been completed yet, we will wait.  Example #2:

                     iodepth_batch_complete_min=0
                     iodepth_batch_complete_max=<iodepth>

              which means that we can retrieve up to the whole submitted queue depth, but if none
              of  I/O  has  been  completed yet, we will NOT wait and immediately exit the system
              call. In this example we simply do polling.

       iodepth_low=int
              The low water mark indicating when to start filling the queue  again.  Defaults  to
              the  same  as  iodepth, meaning that fio will attempt to keep the queue full at all
              times. If iodepth is set to e.g. 16 and iodepth_low is set to 4, then after fio has
              filled  the  queue  of  16  requests,  it will let the depth drain down to 4 before
              starting to fill it again.

       serialize_overlap=bool
              Serialize in-flight I/Os that might otherwise cause  or  suffer  from  data  races.
              When  two or more I/Os are submitted simultaneously, there is no guarantee that the
              I/Os will be processed or completed in the submitted order. Further, if two or more
              of  those  I/Os  are  writes,  any  overlapping  region  between  them  can  become
              indeterminate/undefined on certain storage. These issues can cause verification  to
              fail  erratically  when  at  least  one of the racing I/Os is changing data and the
              overlapping region has a non-zero size.  Setting  serialize_overlap  tells  fio  to
              avoid  provoking this behavior by explicitly serializing in-flight I/Os that have a
              non-zero overlap. Note that setting this option can reduce both performance and the
              iodepth achieved.

              This  option only applies to I/Os issued for a single job except when it is enabled
              along with io_submit_mode=offload. In offload mode,  fio  will  check  for  overlap
              among all I/Os submitted by offload jobs with serialize_overlap enabled.

              Default: false.

       io_submit_mode=str
              This  option  controls  how  fio  submits the I/O to the I/O engine. The default is
              `inline', which means that the fio job threads submit and reap I/O directly. If set
              to  `offload',  the  job threads will offload I/O submission to a dedicated pool of
              I/O threads. This requires some coordination and thus has a bit of extra  overhead,
              especially  for  lower queue depth I/O where it can increase latencies. The benefit
              is that fio can manage submission rates  independently  of  the  device  completion
              rates.  This  avoids  skewed  latency reporting if I/O gets backed up on the device
              side (the coordinated omission problem). Note that this option cannot  reliably  be
              used with async IO engines.

   I/O rate
       thinktime=time
              Stall  the  job  for the specified period of time after an I/O has completed before
              issuing the next. May be used to simulate processing being done by an  application.
              When   the  unit  is  omitted,  the  value  is  interpreted  in  microseconds.  See
              thinktime_blocks, thinktime_iotime and thinktime_spin.

       thinktime_spin=time
              Only valid if thinktime is set - pretend to spend CPU time doing something with the
              data received, before falling back to sleeping for the rest of the period specified
              by thinktime. When the unit is omitted, the value is interpreted in microseconds.

       thinktime_blocks=int
              Only valid if thinktime is set - control how many blocks to issue,  before  waiting
              thinktime usecs. If not set, defaults to 1 which will make fio wait thinktime usecs
              after every block. This effectively makes any queue depth setting redundant,  since
              no  more  than  1  I/O  will  be  queued  before  we have to complete it and do our
              thinktime. In other words, this setting effectively caps the  queue  depth  if  the
              latter is larger.

       thinktime_blocks_type=str
              Only  valid  if  thinktime  is  set  -  control how thinktime_blocks triggers.  The
              default is `complete', which triggers thinktime when fio completes thinktime_blocks
              blocks. If this is set to `issue', then the trigger happens at the issue side.

       thinktime_iotime=time
              Only valid if thinktime is set - control thinktime interval by time.  The thinktime
              stall is repeated  after  IOs  are  executed  for  thinktime_iotime.  For  example,
              `--thinktime_iotime=9s  --thinktime=1s'  repeat  10-second  cycle  with  IOs  for 9
              seconds and stall for 1 second. When  the  unit  is  omitted,  thinktime_iotime  is
              interpreted  as  a  number  of  seconds.   If  this  option  is  used together with
              thinktime_blocks, the thinktime stall is repeated after thinktime_iotime  or  after
              thinktime_blocks IOs, whichever happens first.

       rate=int[,int][,int]
              Cap  the  bandwidth used by this job. The number is in bytes/sec, the normal suffix
              rules apply. Comma-separated values may be specified for reads, writes,  and  trims
              as described in blocksize.

              For  example,  using  `rate=1m,500k'  would  limit  reads to 1MiB/sec and writes to
              500KiB/sec. Capping  only  reads  or  writes  can  be  done  with  `rate=,500k'  or
              `rate=500k,' where the former will only limit writes (to 500KiB/sec) and the latter
              will only limit reads.

       rate_min=int[,int][,int]
              Tell fio to do whatever it can to maintain at least this bandwidth. Failing to meet
              this  requirement  will  cause  the  job  to  exit.  Comma-separated  values may be
              specified for reads, writes, and trims as described in blocksize.

       rate_iops=int[,int][,int]
              Cap the bandwidth to this  number  of  IOPS.  Basically  the  same  as  rate,  just
              specified  independently  of  bandwidth.  If  the  job  is given a block size range
              instead of a fixed value, the smallest block size is used  as  the  metric.  Comma-
              separated  values  may  be  specified  for reads, writes, and trims as described in
              blocksize.

       rate_iops_min=int[,int][,int]
              If fio doesn't meet this rate of I/O, it  will  cause  the  job  to  exit.   Comma-
              separated  values  may  be  specified  for reads, writes, and trims as described in
              blocksize.

       rate_process=str
              This option controls  how  fio  manages  rated  I/O  submissions.  The  default  is
              `linear', which submits I/O in a linear fashion with fixed delays between I/Os that
              gets adjusted based on I/O completion rates. If this is set to `poisson', fio  will
              submit  I/O  based  on  a more real world random request flow, known as the Poisson
              process (https://en.wikipedia.org/wiki/Poisson_point_process). The lambda  will  be
              10^6 / IOPS for the given workload.

       rate_ignore_thinktime=bool
              By default, fio will attempt to catch up to the specified rate setting, if any kind
              of thinktime setting was used. If this option is set,  then  fio  will  ignore  the
              thinktime and continue doing IO at the specified rate, instead of entering a catch-
              up mode after thinktime is done.

       rate_cycle=int
              Average bandwidth for rate and rate_min over this number of milliseconds.  Defaults
              to 1000.

   I/O latency
       latency_target=time
              If  set, fio will attempt to find the max performance point that the given workload
              will run at while maintaining a  latency  below  this  target.  When  the  unit  is
              omitted,   the  value  is  interpreted  in  microseconds.  See  latency_window  and
              latency_percentile.

       latency_window=time
              Used with latency_target to specify the sample  window  that  the  job  is  run  at
              varying  queue  depths to test the performance. When the unit is omitted, the value
              is interpreted in microseconds.

       latency_percentile=float
              The  percentage  of  I/Os  that  must  fall  within  the  criteria   specified   by
              latency_target and latency_window. If not set, this defaults to 100.0, meaning that
              all I/Os must be equal or below to the value set by latency_target.

       latency_run=bool
              Used with latency_target. If false (default), fio will find the highest queue depth
              that  meets  latency_target and exit. If true, fio will continue running and try to
              meet latency_target by adjusting queue depth.

       max_latency=time[,time][,time]
              If set, fio will exit the job with an ETIMEDOUT error if it  exceeds  this  maximum
              latency. When the unit is omitted, the value is interpreted in microseconds. Comma-
              separated values may be specified for reads, writes,  and  trims  as  described  in
              blocksize.

   I/O replay
       write_iolog=str
              Write  the  issued  I/O  patterns  to the specified file. See read_iolog. Specify a
              separate file for each job, otherwise the iologs will be interspersed and the  file
              may be corrupt. This file will be opened in append mode.

       read_iolog=str
              Open  an iolog with the specified filename and replay the I/O patterns it contains.
              This can be used to store a workload and replay it sometime later. The iolog  given
              may  also be a blktrace binary file, which allows fio to replay a workload captured
              by blktrace. See blktrace(8) for how to capture such  logging  data.  For  blktrace
              replay,  the  file  needs  to  be  turned  into  a  blkparse binary data file first
              (`blkparse <device> -o /dev/null -d file_for_fio.bin').  You can specify  a  number
              of files by separating the names with a ':' character.  See the filename option for
              information on how to escape ':' characters within the file names. These files will
              be  sequentially assigned to job clones created by numjobs. '-' is a reserved name,
              meaning read from stdin, notably if filename is set to '-'  which  means  stdin  as
              well, then this flag can't be set to '-'.

       read_iolog_chunked=bool
              Determines  how iolog is read. If false (default) entire read_iolog will be read at
              once. If selected true, input from iolog will be read gradually.  Useful when iolog
              is very large, or it is generated.

       merge_blktrace_file=str
              When  specified,  rather  than replaying the logs passed to read_iolog, the logs go
              through a merge phase which aggregates them into a single blktrace.  The  resulting
              file  is  then passed on as the read_iolog parameter. The intention here is to make
              the order of events consistent. This limits the influence of the scheduler compared
              to replaying multiple blktraces via concurrent jobs.

       merge_blktrace_scalars=float_list
              This  is  a  percentage  based  option  that is index paired with the list of files
              passed to read_iolog. When merging is performed, scale the time of  each  event  by
              the corresponding amount. For example, `--merge_blktrace_scalars="50:100"' runs the
              first trace in halftime and the second trace in realtime. This knob  is  separately
              tunable  from  replay_time_scale which scales the trace during runtime and will not
              change the output of the merge unlike this option.

       merge_blktrace_iters=float_list
              This is a whole number option that is index paired with the list of files passed to
              read_iolog.  When  merging is performed, run each trace for the specified number of
              iterations. For example, `--merge_blktrace_iters="2:1"' runs the  first  trace  for
              two iterations and the second trace for one iteration.

       replay_no_stall=bool
              When  replaying  I/O  with read_iolog the default behavior is to attempt to respect
              the timestamps within the log and replay them with the  appropriate  delay  between
              IOPS.  By  setting this variable fio will not respect the timestamps and attempt to
              replay them as fast as possible while still respecting ordering. The result is  the
              same I/O pattern to a given device, but different timings.

       replay_time_scale=int
              When  replaying  I/O  with  read_iolog,  fio  will honor the original timing in the
              trace. With this option, it's possible to scale the time. It's a percentage option,
              if  set to 50 it means run at 50% the original IO rate in the trace. If set to 200,
              run at twice the original IO rate. Defaults to 100.

       replay_redirect=str
              While replaying I/O patterns using read_iolog the default behavior is to replay the
              IOPS onto the major/minor device that each IOP was recorded from. This is sometimes
              undesirable because on a different machine those major/minor numbers can map  to  a
              different  device.  Changing  hardware  on  the  same  system  can also result in a
              different major/minor mapping.  replay_redirect causes all I/Os to be replayed onto
              the  single  specified  device  regardless of the device it was recorded from. i.e.
              `replay_redirect=/dev/sdc' would cause all I/O in  the  blktrace  or  iolog  to  be
              replayed  onto  `/dev/sdc'.  This  means  multiple  devices will be replayed onto a
              single device, if the trace contains multiple devices. If you want multiple devices
              to  be  replayed concurrently to multiple redirected devices you must blkparse your
              trace into separate traces  and  replay  them  with  independent  fio  invocations.
              Unfortunately  this  also  breaks  the strict time ordering between multiple device
              accesses.

       replay_align=int
              Force alignment of the byte offsets in a trace to this value. The value must  be  a
              power of 2.

       replay_scale=int
              Scale bye offsets down by this factor when replaying traces. Should most likely use
              replay_align as well.

   Threads, processes and job synchronization
       replay_skip=str
              Sometimes it's useful to skip certain IO types in a replay trace.  This  could  be,
              for   instance,  eliminating  the  writes  in  the  trace.  Or  not  replaying  the
              trims/discards, if you are redirecting to a device that doesn't support them.  This
              option takes a comma separated list of read, write, trim, sync.

       thread Fio  defaults  to creating jobs by using fork, however if this option is given, fio
              will create jobs by using  POSIX  Threads'  function  pthread_create(3)  to  create
              threads instead.

       wait_for=str
              If  set, the current job won't be started until all workers of the specified waitee
              job are done.  wait_for operates on  the  job  name  basis,  so  there  are  a  few
              limitations.  First, the waitee must be defined prior to the waiter job (meaning no
              forward references). Second, if a job is being referenced as a waitee, it must have
              a unique name (no duplicate waitees).

       nice=int
              Run  the  job  with the given nice value. See man nice(2).  On Windows, values less
              than -15 set the process class to "High"; -1 through  -15  set  "Above  Normal";  1
              through 15 "Below Normal"; and above 15 "Idle" priority class.

       prio=int
              Set the I/O priority value of this job. Linux limits us to a positive value between
              0 and 7, with 0 being the highest. See  man  ionice(1).  Refer  to  an  appropriate
              manpage  for other operating systems since meaning of priority may differ. For per-
              command priority setting, see the  I/O  engine  specific  `cmdprio_percentage`  and
              `cmdprio` options.

       prioclass=int
              Set  the  I/O  priority class. See man ionice(1). For per-command priority setting,
              see the I/O engine specific `cmdprio_percentage` and `cmdprio_class` options.

       cpus_allowed=str
              Controls the same options as cpumask, but accepts a textual  specification  of  the
              permitted  CPUs  instead  and  CPUs  are indexed from 0. So to use CPUs 0 and 5 you
              would specify `cpus_allowed=0,5'. This option also allows a range  of  CPUs  to  be
              specified  --  say  you  wanted  a binding to CPUs 0, 5, and 8 to 15, you would set
              `cpus_allowed=0,5,8-15'.

              On Windows, when `cpus_allowed' is unset only CPUs  from  fio's  current  processor
              group  will  be  used  and  affinity settings are inherited from the system. An fio
              build configured to target Windows 7 makes options that set  CPUs  processor  group
              aware  and  values  will  set  both  the processor group and a CPU from within that
              group. For example, on a system where processor group 0 has 40 CPUs  and  processor
              group  1  has  32  CPUs, `cpus_allowed' values between 0 and 39 will bind CPUs from
              processor group 0 and `cpus_allowed' values between 40 and 71 will bind  CPUs  from
              processor  group 1. When using `cpus_allowed_policy=shared' all CPUs specified by a
              single `cpus_allowed' option must be from the same processor group. For Windows fio
              builds  not  built  for Windows 7, CPUs will only be selected from (and be relative
              to) whatever processor group fio happens to be  running  in  and  CPUs  from  other
              processor groups cannot be used.

       cpus_allowed_policy=str
              Set  the  policy  of  how  fio  distributes  the  CPUs specified by cpus_allowed or
              cpumask. Two policies are supported:

                     shared All jobs will share the CPU set specified.

                     split  Each job will get a unique CPU from the CPU set.

              shared is the default  behavior,  if  the  option  isn't  specified.  If  split  is
              specified,  then  fio will assign one cpu per job. If not enough CPUs are given for
              the jobs listed, then fio will roundrobin the CPUs in the set.

       cpumask=int
              Set the CPU affinity of this job. The parameter given is a bit mask of allowed CPUs
              the  job  may run on. So if you want the allowed CPUs to be 1 and 5, you would pass
              the decimal value of (1 << 1 | 1 << 5), or 34. See man  sched_setaffinity(2).  This
              may  not  work  on  all supported operating systems or kernel versions. This option
              doesn't work well for a higher CPU count than what you  can  store  in  an  integer
              mask,  so  it  can  only  control  cpus 1-32. For boxes with larger CPU counts, use
              cpus_allowed.

       numa_cpu_nodes=str
              Set this job running on specified NUMA  nodes'  CPUs.  The  arguments  allow  comma
              delimited  list  of cpu numbers, A-B ranges, or `all'. Note, to enable NUMA options
              support, fio must be built on a system with libnuma-dev(el) installed.

       numa_mem_policy=str
              Set this job's memory policy and corresponding NUMA nodes. Format of the arguments:

                     <mode>[:<nodelist>]

              `mode' is one of  the  following  memory  policies:  `default',  `prefer',  `bind',
              `interleave'  or  `local'. For `default' and `local' memory policies, no node needs
              to  be  specified.  For  `prefer',  only  one  node  is  allowed.  For  `bind'  and
              `interleave'  the  `nodelist' may be as follows: a comma delimited list of numbers,
              A-B ranges, or `all'.

       cgroup=str
              Add job to this control group. If it doesn't exist, it will be created. The  system
              must  have  a  mounted  cgroup  blkio  mount point for this to work. If your system
              doesn't have it mounted, you can do so with:

                     # mount -t cgroup -o blkio none /cgroup

       cgroup_weight=int
              Set the weight of the cgroup to this value. See the documentation that  comes  with
              the kernel, allowed values are in the range of 100..1000.

       cgroup_nodelete=bool
              Normally  fio  will  delete the cgroups it has created after the job completion. To
              override this behavior and to leave cgroups around after the  job  completion,  set
              `cgroup_nodelete=1'.  This  can  be  useful  if one wants to inspect various cgroup
              files after job completion. Default: false.

       flow_id=int
              The ID of the flow. If not specified, it defaults to being a global flow. See flow.

       flow=int
              Weight in token-based flow control. If this value is used, then fio  regulates  the
              activity  between  two or more jobs sharing the same flow_id.  Fio attempts to keep
              each job activity proportional to other jobs' activities in the same flow_id group,
              with  respect  to  requested  weight  per  job.   That is, if one job has `flow=3',
              another job has `flow=2' and another with `flow=1`, then there will  be  a  roughly
              3:2:1 ratio in how much one runs vs the others.

       flow_sleep=int
              The  period  of  time, in microseconds, to wait after the flow counter has exceeded
              its proportion before retrying operations.

       stonewall, wait_for_previous
              Wait for preceding jobs in the job file to exit, before starting this one.  Can  be
              used  to  insert  serialization  points  in the job file. A stone wall also implies
              starting a new  reporting  group,  see  group_reporting.  Optionally  you  can  use
              `stonewall=0` to disable or `stonewall=1` to enable it.

       exitall
              By  default,  fio  will  continue  running  all  other  jobs when one job finishes.
              Sometimes this is not the desired action. Setting exitall  will  instead  make  fio
              terminate all jobs in the same group, as soon as one job of that group finishes.

       exit_what=str
              By  default,  fio  will  continue  running  all  other  jobs when one job finishes.
              Sometimes this is not the desired action. Setting exitall  will  instead  make  fio
              terminate  all  jobs  in the same group. The option exit_what allows you to control
              which jobs get terminated when exitall is enabled.  The  default  value  is  group.
              The allowed values are:

                     all    terminates all jobs.

                     group  is the default and does not change the behaviour of exitall.

                     stonewall
                            terminates all currently running jobs across all groups and continues
                            execution with the next stonewalled group.

       exec_prerun=str
              Before running this job, issue the command specified through system(3).  Output  is
              redirected in a file called `jobname.prerun.txt'.

       exec_postrun=str
              After  the  job  completes, issue the command specified though system(3). Output is
              redirected in a file called `jobname.postrun.txt'.

       uid=int
              Instead of running as the invoking user, set the user ID to this value  before  the
              thread/process does any work.

       gid=int
              Set group ID, see uid.

   Verification
       verify_only
              Do  not  perform  specified  workload,  only  verify  data  still  matches previous
              invocation of this workload. This option allows one to check data multiple times at
              a  later  date  without  overwriting it. This option makes sense only for workloads
              that write data, and does not support workloads with the time_based option set.

       do_verify=bool
              Run the verify phase after a write phase. Only valid if  verify  is  set.  Default:
              true.

       verify=str
              If  writing to a file, fio can verify the file contents after each iteration of the
              job. Each verification method also implies verification of special header, which is
              written to the beginning of each block. This header also includes meta information,
              like offset of the block, block number, timestamp  when  block  was  written,  etc.
              verify can be combined with verify_pattern option. The allowed values are:

                     md5    Use  an  md5  sum of the data area and store it in the header of each
                            block.

                     crc64  Use an experimental crc64 sum of the data area and store  it  in  the
                            header of each block.

                     crc32c Use  a crc32c sum of the data area and store it in the header of each
                            block. This will automatically use hardware acceleration (e.g. SSE4.2
                            on  an  x86  or CRC crypto extensions on ARM64) but will fall back to
                            software crc32c if none is found. Generally the fastest checksum  fio
                            supports when hardware accelerated.

                     crc32c-intel
                            Synonym for crc32c.

                     crc32  Use  a  crc32 sum of the data area and store it in the header of each
                            block.

                     crc16  Use a crc16 sum of the data area and store it in the header  of  each
                            block.

                     crc7   Use  a  crc7  sum of the data area and store it in the header of each
                            block.

                     xxhash Use xxhash as the checksum function. Generally the  fastest  software
                            checksum that fio supports.

                     sha512 Use sha512 as the checksum function.

                     sha256 Use sha256 as the checksum function.

                     sha1   Use optimized sha1 as the checksum function.

                     sha3-224
                            Use optimized sha3-224 as the checksum function.

                     sha3-256
                            Use optimized sha3-256 as the checksum function.

                     sha3-384
                            Use optimized sha3-384 as the checksum function.

                     sha3-512
                            Use optimized sha3-512 as the checksum function.

                     meta   This  option is deprecated, since now meta information is included in
                            generic verification header and meta verification happens by default.
                            For  detailed  information see the description of the verify setting.
                            This  option  is  kept  because  of  compatibility's  sake  with  old
                            configurations. Do not use it.

                     pattern
                            Verify  a  strict  pattern.  Normally fio includes a header with some
                            basic information and checksumming, but if this option is  set,  only
                            the specific pattern set with verify_pattern is verified.

                     null   Only   pretend   to   verify.   Useful  for  testing  internals  with
                            `ioengine=null', not for much else.

              This option can be used for repeated burn-in tests of a system to  make  sure  that
              the written data is also correctly read back. If the data direction given is a read
              or random read, fio will assume that it should verify a previously written file. If
              the  data  direction  includes  any  form of write, the verify will be of the newly
              written data.

              To avoid false  verification  errors,  do  not  use  the  norandommap  option  when
              verifying  data  with async I/O engines and I/O depths > 1.  Or use the norandommap
              and the lfsr random generator together to avoid writing to  the  same  offset  with
              multiple outstanding I/Os.

       verify_offset=int
              Swap  the verification header with data somewhere else in the block before writing.
              It is swapped back before verifying.

       verify_interval=int
              Write the verification header at a finer granularity than the blocksize. It will be
              written  for  chunks  the  size  of  verify_interval.  blocksize should divide this
              evenly.

       verify_pattern=str
              If set, fio will fill the I/O buffers with this pattern. Fio  defaults  to  filling
              with  totally  random  bytes,  but  sometimes it's interesting to fill with a known
              pattern for I/O verification purposes. Depending on the width of the  pattern,  fio
              will  fill 1/2/3/4 bytes of the buffer at the time (it can be either a decimal or a
              hex number). The verify_pattern if larger than a 32-bit quantity has to  be  a  hex
              number  that starts with either "0x" or "0X". Use with verify. Also, verify_pattern
              supports %o format, which means that for each block offset will be written and then
              verified back, e.g.:

                     verify_pattern=%o

              Or use combination of everything:

                     verify_pattern=0xff%o"abcd"-12

       verify_fatal=bool
              Normally  fio  will  keep  checking  the entire contents before quitting on a block
              verification failure. If this option is set, fio will exit the  job  on  the  first
              observed failure. Default: false.

       verify_dump=bool
              If  set,  dump  the  contents of both the original data block and the data block we
              read off disk to files. This allows later analysis to inspect  just  what  kind  of
              data corruption occurred. Off by default.

       verify_async=int
              Fio  will  normally verify I/O inline from the submitting thread. This option takes
              an integer describing how many async offload threads to create for I/O verification
              instead,  causing  fio to offload the duty of verifying I/O contents to one or more
              separate threads. If using this offload option, even sync I/O engines  can  benefit
              from  using  an  iodepth  setting  higher  than 1, as it allows them to have I/O in
              flight while verifies are running.  Defaults to 0 async threads, i.e.  verification
              is not asynchronous.

       verify_async_cpus=str
              Tell  fio  to set the given CPU affinity on the async I/O verification threads. See
              cpus_allowed for the format used.

       verify_backlog=int
              Fio will normally verify the written contents of a job that  utilizes  verify  once
              that  job  has  completed. In other words, everything is written then everything is
              read back and verified. You may want to verify continually instead for a variety of
              reasons.  Fio  stores  the meta data associated with an I/O block in memory, so for
              large verify workloads, quite a bit of memory would be used up  holding  this  meta
              data.  If  this  option  is  enabled, fio will write only N blocks before verifying
              these blocks.

       verify_backlog_batch=int
              Control how many blocks fio will verify if verify_backlog is set. If not set,  will
              default  to  the value of verify_backlog (meaning the entire queue is read back and
              verified). If verify_backlog_batch is less than verify_backlog then not all  blocks
              will  be  verified,  if  verify_backlog_batch  is  larger than verify_backlog, some
              blocks will be verified more than once.

       verify_state_save=bool
              When a job exits during the write phase of a  verify  workload,  save  its  current
              state. This allows fio to replay up until that point, if the verify state is loaded
              for the verify read phase. The format of the filename is, roughly:

                     <type>-<jobname>-<jobindex>-verify.state.

              <type> is "local" for a local run, "sock" for a  client/server  socket  connection,
              and  "ip"  (192.168.0.1,  for  instance)  for a networked client/server connection.
              Defaults to true.

       verify_state_load=bool
              If a verify termination trigger was used, fio stores the  current  write  state  of
              each  thread.  This  can  be used at verification time so that fio knows how far it
              should verify. Without this information, fio will run  a  full  verification  pass,
              according to the settings in the job file used. Default false.

       experimental_verify=bool
              Enable  experimental  verification.  Standard verify records I/O metadata for later
              use during the verification phase. Experimental  verify  instead  resets  the  file
              after the write phase and then replays I/Os for the verification phase.

       trim_percentage=int
              Number of verify blocks to discard/trim.

       trim_verify_zero=bool
              Verify that trim/discarded blocks are returned as zeros.

       trim_backlog=int
              Verify that trim/discarded blocks are returned as zeros.

       trim_backlog_batch=int
              Trim this number of I/O blocks.

   Steady state
       steadystate=str:float, ss=str:float
              Define  the  criterion  and limit for assessing steady state performance. The first
              parameter designates the criterion whereas the second parameter sets the threshold.
              When  the  criterion  falls below the threshold for the specified duration, the job
              will stop. For example, `iops_slope:0.1%' will direct fio to terminate the job when
              the  least  squares  regression  slope  falls  below  0.1%  of  the  mean  IOPS. If
              group_reporting is enabled this will apply to all jobs in the group. Below  is  the
              list of available steady state assessment criteria. All assessments are carried out
              using only data from  the  rolling  collection  window.  Threshold  limits  can  be
              expressed as a fixed value or as a percentage of the mean in the collection window.

              When  using  this  feature,  most  jobs  should  include the time_based and runtime
              options or the loops option so that fio does not stop running after it has  covered
              the full size of the specified file(s) or device(s).

                            iops   Collect  IOPS  data.  Stop  the  job  if  all  individual IOPS
                                   measurements are within the specified limit of the  mean  IOPS
                                   (e.g.,  `iops:2' means that all individual IOPS values must be
                                   within 2 of the  mean,  whereas  `iops:0.2%'  means  that  all
                                   individual IOPS values must be within 0.2% of the mean IOPS to
                                   terminate the job).

                            iops_slope
                                   Collect IOPS data and calculate the least  squares  regression
                                   slope.  Stop  the  job  if the slope falls below the specified
                                   limit.

                            bw     Collect  bandwidth  data.  Stop  the  job  if  all  individual
                                   bandwidth  measurements  are within the specified limit of the
                                   mean bandwidth.

                            bw_slope
                                   Collect  bandwidth  data  and  calculate  the  least   squares
                                   regression  slope.  Stop  the job if the slope falls below the
                                   specified limit.

              steadystate_duration=time, ss_dur=time
                     A rolling window of this duration will be used to judge whether steady state
                     has been reached. Data will be collected every ss_interval. The default is 0
                     which disables steady state detection. When the unit is omitted,  the  value
                     is interpreted in seconds.

              steadystate_ramp_time=time, ss_ramp=time
                     Allow  the  job  to  run  for  the  specified duration before beginning data
                     collection for checking the steady  state  job  termination  criterion.  The
                     default is 0. When the unit is omitted, the value is interpreted in seconds.

              steadystate_check_interval=time, ss_interval=time
                     The values suring the rolling window will be collected with a period of this
                     value. If ss_interval is 30s and ss_dur is 300s,  10  measurements  will  be
                     taken.  Default  is  1s  but  that might not converge, especially for slower
                     devices, so set this accordingly. When the unit is  omitted,  the  value  is
                     interpreted in seconds.

   Measurements and reporting
       per_job_logs=bool
              If  set,  this  generates  bw/clat/iops log with per file private filenames. If not
              set, jobs with identical names will share the log filename. Default: true.

       group_reporting
              It may sometimes be interesting to display statistics for groups of jobs as a whole
              instead  of  for  each  individual job. This is especially true if numjobs is used;
              looking at individual thread/process output quickly becomes unwieldy.  To  see  the
              final report per-group instead of per-job, use group_reporting. Jobs in a file will
              be part of the same reporting group, unless if separated  by  a  stonewall,  or  by
              using new_group.

       new_group
              Start a new reporting group. See: group_reporting. If not given, all jobs in a file
              will be part of the same reporting group, unless separated by a stonewall.

       stats=bool
              By default, fio collects and shows final output results for all jobs that  run.  If
              this option is set to 0, then fio will ignore it in the final stat output.

       write_bw_log=str
              If  given,  write  a  bandwidth  log for this job. Can be used to store data of the
              bandwidth of the jobs in their lifetime.

              If no str argument is given, the default filename of `jobname_type.x.log' is  used.
              Even  when  the argument is given, fio will still append the type of log. So if one
              specifies:

                     write_bw_log=foo

              The actual log name will be `foo_bw.x.log' where `x' is the index of the job (1..N,
              where  N  is  the number of jobs). If per_job_logs is false, then the filename will
              not include the `.x` job index.

              The included fio_generate_plots script uses gnuplot to turn these text  files  into
              nice graphs. See the LOG FILE FORMATS section for how data is structured within the
              file.

       write_lat_log=str
              Same  as  write_bw_log,  except  this  option   creates   I/O   submission   (e.g.,
              `name_slat.x.log'),   completion   (e.g.,   `name_clat.x.log'),  and  total  (e.g.,
              `name_lat.x.log') latency files instead. See write_bw_log  for  details  about  the
              filename  format and the LOG FILE FORMATS section for how data is structured within
              the files.

       write_hist_log=str
              Same as write_bw_log but writes an I/O completion  latency  histogram  file  (e.g.,
              `name_hist.x.log')  instead. Note that this file will be empty unless log_hist_msec
              has also been set.  See write_bw_log for details about the filename format and  the
              LOG FILE FORMATS section for how data is structured within the file.

       write_iops_log=str
              Same  as  write_bw_log,  but writes an IOPS file (e.g.  `name_iops.x.log`) instead.
              Because fio defaults to individual I/O logging, the value entry  in  the  IOPS  log
              will  be  1  unless  windowed  logging  (see  log_avg_msec)  has  been enabled. See
              write_bw_log for details about the filename format and LOG  FILE  FORMATS  for  how
              data is structured within the file.

       log_entries=int
              By  default,  fio  will  log an entry in the iops, latency, or bw log for every I/O
              that completes. The initial number of I/O  log  entries  is  1024.   When  the  log
              entries  are all used, new log entries are dynamically allocated.  This dynamic log
              entry allocation may negatively impact time-related statistics  such  as  I/O  tail
              latencies   (e.g.   99.9th  percentile  completion  latency).  This  option  allows
              specifying a larger initial number of log entries to avoid run-time  allocation  of
              new  log  entries, resulting in more precise time-related I/O statistics.  Also see
              log_avg_msec as well. Defaults to 1024.

       log_avg_msec=int
              By default, fio will log an entry in the iops, latency, or bw  log  for  every  I/O
              that completes. When writing to the disk log, that can quickly grow to a very large
              size. Setting this option makes fio average the each log entry over  the  specified
              period  of  time,  reducing  the  resolution of the log. See log_max_value as well.
              Defaults to 0, logging all entries.  Also see LOG FILE FORMATS section.

       log_hist_msec=int
              Same as log_avg_msec, but logs entries for completion latency histograms. Computing
              latency  percentiles  from  averages of intervals using log_avg_msec is inaccurate.
              Setting this option makes fio log histogram entries over the  specified  period  of
              time, reducing log sizes for high IOPS devices while retaining percentile accuracy.
              See log_hist_coarseness  and  write_hist_log  as  well.   Defaults  to  0,  meaning
              histogram logging is disabled.

       log_hist_coarseness=int
              Integer  ranging  from  0  to  6,  defining the coarseness of the resolution of the
              histogram logs enabled with log_hist_msec. For each increment  in  coarseness,  fio
              outputs  half  as  many  bins. Defaults to 0, for which histogram logs contain 1216
              latency bins. See LOG FILE FORMATS section.

       log_max_value=bool
              If log_avg_msec is set, fio logs the average over that window. If you instead  want
              to  log  the  maximum  value,  set  this  option  to 1. Defaults to 0, meaning that
              averaged values are logged.

       log_offset=bool
              If this is set, the iolog options will include the byte offset for the I/O entry as
              well  as  the other data values. Defaults to 0 meaning that offsets are not present
              in logs. Also see LOG FILE FORMATS section.

       log_prio=bool
              If this is set, the iolog options will include the I/O priority for the  I/O  entry
              as well as the other data values. Defaults to 0 meaning that I/O priorities are not
              present in logs. Also see LOG FILE FORMATS section.

       log_compression=int
              If this is set, fio will compress the I/O logs as  it  goes,  to  keep  the  memory
              footprint  lower.  When a log reaches the specified size, that chunk is removed and
              compressed in the background. Given that I/O logs are fairly  highly  compressible,
              this  yields  a  nice  memory  savings  for  longer  runs. The downside is that the
              compression will consume some background CPU cycles, so  it  may  impact  the  run.
              This,  however,  is  also  true if the logging ends up consuming most of the system
              memory. So pick your poison. The I/O logs are saved normally at the end of  a  run,
              by  decompressing  the  chunks  and  storing  them  in the specified log file. This
              feature depends on the availability of zlib.

       log_compression_cpus=str
              Define the set of CPUs that are allowed to handle online log  compression  for  the
              I/O jobs. This can provide better isolation between performance sensitive jobs, and
              background compression work. See cpus_allowed for the format used.

       log_store_compressed=bool
              If set, fio will  store  the  log  files  in  a  compressed  format.  They  can  be
              decompressed  with  fio,  using the --inflate-log command line parameter. The files
              will be stored with a `.fz' suffix.

       log_unix_epoch=bool
              If set, fio will log  Unix  timestamps  to  the  log  files  produced  by  enabling
              write_type_log for each log type, instead of the default zero-based timestamps.

       log_alternate_epoch=bool
              If  set,  fio will log timestamps based on the epoch used by the clock specified in
              the log_alternate_epoch_clock_id option, to the  log  files  produced  by  enabling
              write_type_log for each log type, instead of the default zero-based timestamps.

       log_alternate_epoch_clock_id=int
              Specifies the clock_id to be used by clock_gettime to obtain the alternate epoch if
              either Blog_unix_epoch or log_alternate_epoch are true. Otherwise  has  no  effect.
              Default value is 0, or CLOCK_REALTIME.

       block_error_percentiles=bool
              If  set, record errors in trim block-sized units from writes and trims and output a
              histogram of how many trims it took to get to errors, and what kind  of  error  was
              encountered.

       bwavgtime=int
              Average  the  calculated  bandwidth  over  the  given  time.  Value is specified in
              milliseconds. If the job also does bandwidth logging through write_bw_log, then the
              minimum of this option and log_avg_msec will be used. Default: 500ms.

       iopsavgtime=int
              Average   the   calculated  IOPS  over  the  given  time.  Value  is  specified  in
              milliseconds. If the job also does IOPS logging through  write_iops_log,  then  the
              minimum of this option and log_avg_msec will be used. Default: 500ms.

       disk_util=bool
              Generate disk utilization statistics, if the platform supports it.  Default: true.

       disable_lat=bool
              Disable  measurements  of  total  latency numbers. Useful only for cutting back the
              number of calls to gettimeofday(2), as that does impact performance at really  high
              IOPS  rates.  Note  that  to  really get rid of a large amount of these calls, this
              option must be used with disable_slat and disable_bw_measurement as well.

       disable_clat=bool
              Disable measurements of completion latency numbers. See disable_lat.

       disable_slat=bool
              Disable measurements of submission latency numbers. See disable_lat.

       disable_bw_measurement=bool, disable_bw=bool
              Disable measurements of throughput/bandwidth numbers. See disable_lat.

       slat_percentiles=bool
              Report submission latency percentiles.  Submission  latency  is  not  recorded  for
              synchronous ioengines.

       clat_percentiles=bool
              Report completion latency percentiles.

       lat_percentiles=bool
              Report  total  latency  percentiles. Total latency is the sum of submission latency
              and completion latency.

       percentile_list=float_list
              Overwrite the default list  of  percentiles  for  latencies  and  the  block  error
              histogram.  Each  number  is  a floating point number in the range (0,100], and the
              maximum length of the list is 20. Use ':' to separate  the  numbers.  For  example,
              `--percentile_list=99.5:99.9'  will cause fio to report the latency durations below
              which 99.5% and 99.9% of the observed latencies fell, respectively.

       significant_figures=int
              If using --output-format of `normal', set the significant figures  to  this  value.
              Higher values will yield more precise IOPS and throughput units, while lower values
              will round. Requires a minimum value of 1 and a maximum value of 10. Defaults to 4.

   Error handling
       exitall_on_error
              When one job finishes in error, terminate the rest. The default is to wait for each
              job to finish.

       continue_on_error=str
              Normally  fio  will  exit  the job on the first observed failure. If this option is
              set, fio will continue the job when there is a 'non-fatal error'  (EIO  or  EILSEQ)
              until  the  runtime  is  exceeded  or  the I/O size specified is completed. If this
              option is used, there are two more stats that are appended, the total  error  count
              and the first error. The error field given in the stats is the first error that was
              hit during the run.

              Note: a write error from the device may go unnoticed by fio when using buffered IO,
              as  the  write()  (or  similar) system call merely dirties the kernel pages, unless
              `sync' or `direct' is used. Device IO errors occur when the dirty data is  actually
              written  out to disk. If fully sync writes aren't desirable, `fsync' or `fdatasync'
              can be used as well. This is specific to writes, as reads are always synchronous.

                     The allowed values are:

                                   none   Exit on any I/O or verify errors.

                                   read   Continue on read errors, exit on all others.

                                   write  Continue on write errors, exit on all others.

                                   io     Continue on any I/O error, exit on all others.

                                   verify Continue on verify errors, exit on all others.

                                   all    Continue on all errors.

                                   0      Backward-compatible alias for 'none'.

                                   1      Backward-compatible alias for 'all'.

                     ignore_error=str
                            Sometimes you want to ignore some errors during test in that case you
                            can  specify  error  list  for each error type, instead of only being
                            able to ignore the default 'non-fatal error' using continue_on_error.
                            `ignore_error=READ_ERR_LIST,WRITE_ERR_LIST,VERIFY_ERR_LIST'    errors
                            for given error type is separated  with  ':'.  Error  may  be  symbol
                            ('ENOSPC', 'ENOMEM') or integer. Example:

                                   ignore_error=EAGAIN,ENOSPC:122

                            This  option will ignore EAGAIN from READ, and ENOSPC and 122(EDQUOT)
                            from WRITE. This option works by  overriding  continue_on_error  with
                            the list of errors for each error type if any.

                     error_dump=bool
                            If  set dump every error even if it is non fatal, true by default. If
                            disabled only fatal error will be dumped.

   Running predefined workloads
       Fio includes predefined profiles that mimic the I/O workloads generated by other tools.

       profile=str
              The predefined workload to run. Current profiles are:

                     tiobench
                            Threaded I/O bench (tiotest/tiobench) like workload.

                     act    Aerospike Certification Tool (ACT) like workload.

       To view a profile's additional options use --cmdhelp after  specifying  the  profile.  For
       example:

              $ fio --profile=act --cmdhelp

   Act profile options
       device-names=str
              Devices to use.

       load=int
              ACT load multiplier. Default: 1.

       test-duration=time
              How long the entire test takes to run. When the unit is omitted, the value is given
              in seconds. Default: 24h.

       threads-per-queue=int
              Number of read I/O threads per device. Default: 8.

       read-req-num-512-blocks=int
              Number of 512B blocks to read at the time. Default: 3.

       large-block-op-kbytes=int
              Size of large block ops in KiB (writes). Default: 131072.

       prep   Set to run ACT prep phase.

   Tiobench profile options
       size=str
              Size in MiB.

       block=int
              Block size in bytes. Default: 4096.

       numruns=int
              Number of runs.

       dir=str
              Test directory.

       threads=int
              Number of threads.

OUTPUT

       Fio spits out a lot of output. While running, fio will display  the  status  of  the  jobs
       created. An example of that would be:

                 Jobs: 1 (f=1): [_(1),M(1)][24.8%][r=20.5MiB/s,w=23.5MiB/s][r=82,w=94 IOPS][eta 01m:31s]

       The  characters  inside the first set of square brackets denote the current status of each
       thread. The first character is the first job defined in the job file, and  so  forth.  The
       possible values (in typical life cycle order) are:

              P      Thread setup, but not started.
              C      Thread created.
              I      Thread initialized, waiting or generating necessary data.
              p      Thread running pre-reading file(s).
              /      Thread is in ramp period.
              R      Running, doing sequential reads.
              r      Running, doing random reads.
              W      Running, doing sequential writes.
              w      Running, doing random writes.
              M      Running, doing mixed sequential reads/writes.
              m      Running, doing mixed random reads/writes.
              D      Running, doing sequential trims.
              d      Running, doing random trims.
              F      Running, currently waiting for fsync(2).
              V      Running, doing verification of written data.
              f      Thread finishing.
              E      Thread exited, not reaped by main thread yet.
              -      Thread reaped.
              X      Thread reaped, exited with an error.
              K      Thread reaped, exited due to signal.

       Fio  will condense the thread string as not to take up more space on the command line than
       needed. For instance, if you have 10 readers and 10 writers running, the output would look
       like this:

                 Jobs: 20 (f=20): [R(10),W(10)][4.0%][r=20.5MiB/s,w=23.5MiB/s][r=82,w=94 IOPS][eta 57m:36s]

       Note  that  the status string is displayed in order, so it's possible to tell which of the
       jobs are currently doing what. In the example above this means that jobs 1--10 are readers
       and 11--20 are writers.

       The  other  values  are fairly self explanatory -- number of threads currently running and
       doing I/O, the number of currently open files (f=), the estimated  completion  percentage,
       the rate of I/O since last check (read speed listed first, then write speed and optionally
       trim speed) in terms of bandwidth and IOPS, and time to completion for the current running
       group. It's impossible to estimate runtime of the following groups (if any).

       When  fio is done (or interrupted by Ctrl-C), it will show the data for each thread, group
       of threads, and disks in that order. For each overall thread (or group) the  output  looks
       like:

                 Client1: (groupid=0, jobs=1): err= 0: pid=16109: Sat Jun 24 12:07:54 2017
                   write: IOPS=88, BW=623KiB/s (638kB/s)(30.4MiB/50032msec)
                     slat (nsec): min=500, max=145500, avg=8318.00, stdev=4781.50
                     clat (usec): min=170, max=78367, avg=4019.02, stdev=8293.31
                      lat (usec): min=174, max=78375, avg=4027.34, stdev=8291.79
                     clat percentiles (usec):
                      |  1.00th=[  302],  5.00th=[  326], 10.00th=[  343], 20.00th=[  363],
                      | 30.00th=[  392], 40.00th=[  404], 50.00th=[  416], 60.00th=[  445],
                      | 70.00th=[  816], 80.00th=[ 6718], 90.00th=[12911], 95.00th=[21627],
                      | 99.00th=[43779], 99.50th=[51643], 99.90th=[68682], 99.95th=[72877],
                      | 99.99th=[78119]
                    bw (  KiB/s): min=  532, max=  686, per=0.10%, avg=622.87, stdev=24.82, samples=  100
                    iops        : min=   76, max=   98, avg=88.98, stdev= 3.54, samples=  100
                   lat (usec)   : 250=0.04%, 500=64.11%, 750=4.81%, 1000=2.79%
                   lat (msec)   : 2=4.16%, 4=1.84%, 10=4.90%, 20=11.33%, 50=5.37%
                   lat (msec)   : 100=0.65%
                   cpu          : usr=0.27%, sys=0.18%, ctx=12072, majf=0, minf=21
                   IO depths    : 1=85.0%, 2=13.1%, 4=1.8%, 8=0.1%, 16=0.0%, 32=0.0%, >=64=0.0%
                      submit    : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
                      complete  : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
                      issued rwt: total=0,4450,0, short=0,0,0, dropped=0,0,0
                      latency   : target=0, window=0, percentile=100.00%, depth=8

       The  job  name (or first job's name when using group_reporting) is printed, along with the
       group id, count of jobs being aggregated, last error id seen (which is 0 when there are no
       errors),  pid/tid  of  that thread and the time the job/group completed. Below are the I/O
       statistics for each data direction performed (showing writes in the example above). In the
       order listed, they denote:

              read/write/trim
                     The  string before the colon shows the I/O direction the statistics are for.
                     IOPS is the average I/Os performed per second. BW is the  average  bandwidth
                     rate shown as: value in power of 2 format (value in power of 10 format). The
                     last two values show: (total I/O performed in power of 2 format / runtime of
                     that thread).

              slat   Submission  latency (min being the minimum, max being the maximum, avg being
                     the average, stdev being the standard deviation). This is the time  it  took
                     to  submit  the  I/O.  For sync I/O this row is not displayed as the slat is
                     really the completion latency (since queue/complete is one operation there).
                     This  value can be in nanoseconds, microseconds or milliseconds --- fio will
                     choose the most appropriate base  and  print  that  (in  the  example  above
                     nanoseconds  was  the  best  scale).  Note:  in --minimal mode latencies are
                     always expressed in microseconds.

              clat   Completion  latency.  Same  names  as  slat,  this  denotes  the  time  from
                     submission  to completion of the I/O pieces. For sync I/O, clat will usually
                     be equal (or very close) to 0, as  the  time  from  submit  to  complete  is
                     basically just CPU time (I/O has already been done, see slat explanation).

              lat    Total  latency. Same names as slat and clat, this denotes the time from when
                     fio created the I/O unit to completion of the I/O operation.

              bw     Bandwidth statistics based on  measurements  from  discrete  intervals.  Fio
                     continuosly  monitors  bytes  transferred  and  I/O operations completed. By
                     default  fio  calculates  bandwidth  in  each  half-second   interval   (see
                     bwavgtime)  and  reports  descriptive  statistics for the measurements here.
                     Same names as the xlat stats, but also includes the number of samples  taken
                     (samples)  and  an  approximate percentage of total aggregate bandwidth this
                     thread received in its group (per). This last value is only really useful if
                     the  threads  in  this  group  are  on  the  same  disk, since they are then
                     competing for disk access.

              iops   IOPS statistics based on measurements from discrete intervals.  For  details
                     see the description for bw above. See iopsavgtime to control the duration of
                     the intervals.  Same values reported here as for bw except for percentage.

              lat (nsec/usec/msec)
                     The distribution of I/O completion latencies. This is the time from when I/O
                     leaves  fio  and when it gets completed. Unlike the separate read/write/trim
                     sections above, the data here and in the remaining  sections  apply  to  all
                     I/Os  for  the  reporting  group.  250=0.04%  means  that  0.04% of the I/Os
                     completed in under 250us. 500=64.11% means that 64.11% of the I/Os  required
                     250 to 499us for completion.

              cpu    CPU  usage.  User and system time, along with the number of context switches
                     this thread went through, usage of system and user  time,  and  finally  the
                     number  of  major  and  minor  page  faults. The CPU utilization numbers are
                     averages for the jobs in that reporting group, while the context  and  fault
                     counters are summed.

              IO depths
                     The  distribution  of  I/O  depths  over  the  job lifetime. The numbers are
                     divided into powers of 2 and each entry covers depths from that value up  to
                     those  that are lower than the next entry -- e.g., 16= covers depths from 16
                     to 31. Note that the range covered by a  depth  distribution  entry  can  be
                     different   to   the   range   covered  by  the  equivalent  submit/complete
                     distribution entry.

              IO submit
                     How many pieces of I/O were submitting in a single submit call.  Each  entry
                     denotes  that  amount  and  below, until the previous entry -- e.g., 16=100%
                     means that we submitted anywhere between 9 to 16 I/Os per submit call.  Note
                     that  the  range  covered by a submit distribution entry can be different to
                     the range covered by the equivalent depth distribution entry.

              IO complete
                     Like the above submit number, but for completions instead.

              IO issued rwt
                     The number of read/write/trim requests issued, and how  many  of  them  were
                     short or dropped.

              IO latency
                     These  values are for latency_target and related options. When these options
                     are engaged, this section describes the  I/O  depth  required  to  meet  the
                     specified latency target.

       After  each  client has been listed, the group statistics are printed. They will look like
       this:

                 Run status group 0 (all jobs):
                    READ: bw=20.9MiB/s (21.9MB/s), 10.4MiB/s-10.8MiB/s (10.9MB/s-11.3MB/s), io=64.0MiB (67.1MB), run=2973-3069msec
                   WRITE: bw=1231KiB/s (1261kB/s), 616KiB/s-621KiB/s (630kB/s-636kB/s), io=64.0MiB (67.1MB), run=52747-53223msec

       For each data direction it prints:

              bw     Aggregate bandwidth of threads in this group followed  by  the  minimum  and
                     maximum  bandwidth  of  all  the  threads  in this group.  Values outside of
                     brackets are power-of-2 format and those within are the equivalent value  in
                     a power-of-10 format.

              io     Aggregate I/O performed of all threads in this group. The format is the same
                     as bw.

              run    The smallest and longest runtimes of the threads in this group.

       And finally, the disk statistics are printed. This is Linux specific.  They will look like
       this:

                   Disk stats (read/write):
                     sda: ios=16398/16511, merge=30/162, ticks=6853/819634, in_queue=826487, util=100.00%

       Each value is printed for both reads and writes, with reads first. The numbers denote:

              ios    Number of I/Os performed by all groups.

              merge  Number of merges performed by the I/O scheduler.

              ticks  Number of ticks we kept the disk busy.

              in_queue
                     Total time spent in the disk queue.

              util   The  disk  utilization.  A  value  of  100%  means  we  kept  the  disk busy
                     constantly, 50% would be a disk idling half of the time.

       It is also possible to get fio to dump the current output while  it  is  running,  without
       terminating  the  job.  To  do  that, send fio the USR1 signal. You can also get regularly
       timed dumps by using the --status-interval parameter, or by  creating  a  file  in  `/tmp'
       named  `fio-dump-status'.  If  fio  sees this file, it will unlink it and dump the current
       output status.

TERSE OUTPUT

       For scripted usage where you typically want to generate tables or graphs of  the  results,
       fio can output the results in a semicolon separated format. The format is one long line of
       values, such as:

                 2;card0;0;0;7139336;121836;60004;1;10109;27.932460;116.933948;220;126861;3495.446807;1085.368601;226;126864;3523.635629;1089.012448;24063;99944;50.275485%;59818.274627;5540.657370;7155060;122104;60004;1;8338;29.086342;117.839068;388;128077;5032.488518;1234.785715;391;128085;5061.839412;1236.909129;23436;100928;50.287926%;59964.832030;5644.844189;14.595833%;19.394167%;123706;0;7313;0.1%;0.1%;0.1%;0.1%;0.1%;0.1%;100.0%;0.00%;0.00%;0.00%;0.00%;0.00%;0.00%;0.01%;0.02%;0.05%;0.16%;6.04%;40.40%;52.68%;0.64%;0.01%;0.00%;0.01%;0.00%;0.00%;0.00%;0.00%;0.00%
                 A description of this job goes here.

       The job description (if provided) follows on a second line for terse v2.   It  appears  on
       the same line for other terse versions.

       To enable terse output, use the --minimal or `--output-format=terse' command line options.
       The first value is the version of the terse output format. If the output has to be changed
       for some reason, this number will be incremented by 1 to signify that change.

       Split  up,  the  format  is  as  follows  (comments  in  brackets  denote when a field was
       introduced or whether it's specific to some terse version):

                      terse version, fio version [v3], jobname, groupid, error

              READ status:

                      Total IO (KiB), bandwidth (KiB/sec), IOPS, runtime (msec)
                      Submission latency: min, max, mean, stdev (usec)
                      Completion latency: min, max, mean, stdev (usec)
                      Completion latency percentiles: 20 fields (see below)
                      Total latency: min, max, mean, stdev (usec)
                      Bw (KiB/s): min, max, aggregate percentage of total, mean, stdev, number of samples [v5]
                      IOPS [v5]: min, max, mean, stdev, number of samples

              WRITE status:

                      Total IO (KiB), bandwidth (KiB/sec), IOPS, runtime (msec)
                      Submission latency: min, max, mean, stdev (usec)
                      Completion latency: min, max, mean, stdev (usec)
                      Completion latency percentiles: 20 fields (see below)
                      Total latency: min, max, mean, stdev (usec)
                      Bw (KiB/s): min, max, aggregate percentage of total, mean, stdev, number of samples [v5]
                      IOPS [v5]: min, max, mean, stdev, number of samples

              TRIM status [all but version 3]:

                      Fields are similar to READ/WRITE status.

              CPU usage:

                      user, system, context switches, major faults, minor faults

              I/O depths:

                      <=1, 2, 4, 8, 16, 32, >=64

              I/O latencies microseconds:

                      <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000

              I/O latencies milliseconds:

                      <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, 2000, >=2000

              Disk utilization [v3]:

                      disk name, read ios, write ios, read merges, write merges, read ticks, write ticks, time spent in queue, disk utilization percentage

              Additional Info (dependent on continue_on_error, default off):

                      total # errors, first error code

              Additional Info (dependent on description being set):

                      Text description

       Completion latency percentiles can be a grouping of up to 20 sets, so for the terse output
       fio writes all of them. Each field will look like this:

                 1.00%=6112

       which is the Xth percentile, and the `usec' latency associated with it.

       For  Disk  utilization,  all disks used by fio are shown. So for each disk there will be a
       disk utilization section.

       Below is a single line containing short names for each of the fields in the minimal output
       v3, separated by semicolons:

                 terse_version_3;fio_version;jobname;groupid;error;read_kb;read_bandwidth_kb;read_iops;read_runtime_ms;read_slat_min_us;read_slat_max_us;read_slat_mean_us;read_slat_dev_us;read_clat_min_us;read_clat_max_us;read_clat_mean_us;read_clat_dev_us;read_clat_pct01;read_clat_pct02;read_clat_pct03;read_clat_pct04;read_clat_pct05;read_clat_pct06;read_clat_pct07;read_clat_pct08;read_clat_pct09;read_clat_pct10;read_clat_pct11;read_clat_pct12;read_clat_pct13;read_clat_pct14;read_clat_pct15;read_clat_pct16;read_clat_pct17;read_clat_pct18;read_clat_pct19;read_clat_pct20;read_tlat_min_us;read_lat_max_us;read_lat_mean_us;read_lat_dev_us;read_bw_min_kb;read_bw_max_kb;read_bw_agg_pct;read_bw_mean_kb;read_bw_dev_kb;write_kb;write_bandwidth_kb;write_iops;write_runtime_ms;write_slat_min_us;write_slat_max_us;write_slat_mean_us;write_slat_dev_us;write_clat_min_us;write_clat_max_us;write_clat_mean_us;write_clat_dev_us;write_clat_pct01;write_clat_pct02;write_clat_pct03;write_clat_pct04;write_clat_pct05;write_clat_pct06;write_clat_pct07;write_clat_pct08;write_clat_pct09;write_clat_pct10;write_clat_pct11;write_clat_pct12;write_clat_pct13;write_clat_pct14;write_clat_pct15;write_clat_pct16;write_clat_pct17;write_clat_pct18;write_clat_pct19;write_clat_pct20;write_tlat_min_us;write_lat_max_us;write_lat_mean_us;write_lat_dev_us;write_bw_min_kb;write_bw_max_kb;write_bw_agg_pct;write_bw_mean_kb;write_bw_dev_kb;cpu_user;cpu_sys;cpu_csw;cpu_mjf;cpu_minf;iodepth_1;iodepth_2;iodepth_4;iodepth_8;iodepth_16;iodepth_32;iodepth_64;lat_2us;lat_4us;lat_10us;lat_20us;lat_50us;lat_100us;lat_250us;lat_500us;lat_750us;lat_1000us;lat_2ms;lat_4ms;lat_10ms;lat_20ms;lat_50ms;lat_100ms;lat_250ms;lat_500ms;lat_750ms;lat_1000ms;lat_2000ms;lat_over_2000ms;disk_name;disk_read_iops;disk_write_iops;disk_read_merges;disk_write_merges;disk_read_ticks;write_ticks;disk_queue_time;disk_util

       In  client/server  mode  terse output differs from what appears when jobs are run locally.
       Disk utilization data is omitted from the standard terse  output  and  for  v3  and  later
       appears on its own separate line at the end of each terse reporting cycle.

JSON OUTPUT

       The  json output format is intended to be both human readable and convenient for automated
       parsing. For the most part its sections mirror those of the  normal  output.  The  runtime
       value is reported in msec and the bw value is reported in 1024 bytes per second units.

JSON+ OUTPUT

       The  json+ output format is identical to the json output format except that it adds a full
       dump of the completion latency bins. Each bins object contains a set of (key, value) pairs
       where  keys  are latency durations and values count how many I/Os had completion latencies
       of the corresponding duration. For example, consider:

              "bins" : { "87552" : 1, "89600" : 1, "94720" : 1, "96768" : 1, "97792" : 1, "99840"
              :  1, "100864" : 2, "103936" : 6, "104960" : 534, "105984" : 5995, "107008" : 7529,
              ... }

       This data indicates that  one  I/O  required  87,552ns  to  complete,  two  I/Os  required
       100,864ns to complete, and 7529 I/Os required 107,008ns to complete.

       Also  included  with  fio is a Python script fio_jsonplus_clat2csv that takes json+ output
       and generates CSV-formatted latency data suitable for plotting.

       The latency durations actually represent the midpoints of latency intervals.  For  details
       refer to `stat.h' in the fio source.

TRACE FILE FORMAT

       There  are  two  trace  file  format  that  you  can  encounter.  The older (v1) format is
       unsupported since version 1.20-rc3 (March 2008). It will still be described below in  case
       that you get an old trace and want to understand it.

       In any case the trace is a simple text file with a single action per line.

       Trace file format v1
              Each line represents a single I/O action in the following format:

                     rw, offset, length

              where  `rw=0/1'  for  read/write,  and  the  `offset' and `length' entries being in
              bytes.

              This format is not supported in fio versions >= 1.20-rc3.

       Trace file format v2
              The second version of the trace file format was  added  in  fio  version  1.17.  It
              allows  one to access more than one file per trace and has a bigger set of possible
              file actions.

              The first line of the trace file has to be:

                     "fio version 2 iolog"

              Following this can be lines in two different formats, which are described below.

              The file management format:
                     filename action

                     The `filename' is given as an absolute path. The  `action'  can  be  one  of
                     these:

                            add    Add the given `filename' to the trace.

                            open   Open the file with the given `filename'. The `filename' has to
                                   have been added with the add action before.

                            close  Close the file with the given `filename'. The file has to have
                                   been opened before.

              The file I/O action format:
                     filename action offset length

                     The  `filename' is given as an absolute path, and has to have been added and
                     opened before it can be used with this format. The `offset' and `length' are
                     given in bytes. The `action' can be one of these:

                            wait   Wait  for  `offset'  microseconds.  Everything  below  100  is
                                   discarded.  The  time  is  relative  to  the  previous  `wait'
                                   statement.  Note  that  action  `wait`  is  not  allowed as of
                                   version  3,  as  the  same  behavior  can  be  achieved  using
                                   timestamps.

                            read   Read `length' bytes beginning from `offset'.

                            write  Write `length' bytes beginning from `offset'.

                            sync   fsync(2) the file.

                            datasync
                                   fdatasync(2) the file.

                            trim   Trim  the  given  file  from  the  given `offset' for `length'
                                   bytes.

       Trace file format v3
              The third version of the trace file format was added in fio version 3.31. It forces
              each action to have a timestamp associated with it.

              The first line of the trace file has to be:

                     "fio version 3 iolog"

              Following this can be lines in two different formats, which are described below.

              The file management format:
                     timestamp filename action

              The file I/O action format:
                     timestamp filename action offset length

                     The  `timestamp`  is  relative to the beginning of the run (ie starts at 0).
                     The `filename`, `action`, `offset` and `length`  are identical to version 2,
                     except that version 3 does not allow the `wait` action.

I/O REPLAY - MERGING TRACES

       Colocation  is  a  common  practice  used to get the most out of a machine.  Knowing which
       workloads play nicely with each other and which ones don't is a much  harder  task.  While
       fio  can replay workloads concurrently via multiple jobs, it leaves some variability up to
       the scheduler making results harder to reproduce. Merging is a way to make  the  order  of
       events consistent.

       Merging  is  integrated  into I/O replay and done when a merge_blktrace_file is specified.
       The list of files passed to read_iolog go through the merge process and  output  a  single
       file  stored  to  the  specified file. The output file is passed on as if it were the only
       file passed to read_iolog. An example would look like:

              $ fio --read_iolog="<file1>:<file2>" --merge_blktrace_file="<output_file>"

       Creating only the merged file can be done by passing  the  command  line  argument  merge-
       blktrace-only.

       Scaling traces can be done to see the relative impact of any particular trace being slowed
       down or sped up. merge_blktrace_scalars takes in a  colon  separated  list  of  percentage
       scalars. It is index paired with the files passed to read_iolog.

       With  scaling,  it  may be desirable to match the running time of all traces.  This can be
       done  with  merge_blktrace_iters.  It  is  index  paired   with   read_iolog   just   like
       merge_blktrace_scalars.

       In  an  example, given two traces, A and B, each 60s long. If we want to see the impact of
       trace A issuing IOs twice as fast and repeat trace A over the  runtime  of  trace  B,  the
       following can be done:

              $   fio   --read_iolog="<trace_a>:"<trace_b>"  --merge_blktrace_file"<output_file>"
              --merge_blktrace_scalars="50:100" --merge_blktrace_iters="2:1"

       This runs trace A at 2x the speed twice for approximately the same runtime as a single run
       of trace B.

CPU IDLENESS PROFILING

       In  some cases, we want to understand CPU overhead in a test. For example, we test patches
       for the specific goodness of whether they reduce CPU  usage.   Fio  implements  a  balloon
       approach  to create a thread per CPU that runs at idle priority, meaning that it only runs
       when nobody else needs the cpu.  By measuring the amount of work completed by the  thread,
       idleness of each CPU can be derived accordingly.

       An  unit work is defined as touching a full page of unsigned characters. Mean and standard
       deviation of time to complete an unit work is reported in "unit work" section. Options can
       be  chosen  to  report  detailed percpu idleness or overall system idleness by aggregating
       percpu stats.

VERIFICATION AND TRIGGERS

       Fio is usually run in one of two ways, when data verification is  done.  The  first  is  a
       normal write job of some sort with verify enabled. When the write phase has completed, fio
       switches to reads and verifies everything it wrote. The second model is running  just  the
       write  phase, and then later on running the same job (but with reads instead of writes) to
       repeat the same I/O patterns and verify the contents. Both of these methods depend on  the
       write phase being completed, as fio otherwise has no idea how much data was written.

       With  verification  triggers, fio supports dumping the current write state to local files.
       Then a subsequent read verify workload can load this state and know exactly where to stop.
       This  is useful for testing cases where power is cut to a server in a managed fashion, for
       instance.

       A verification trigger consists of two things:

              1) Storing the write state of each job.

              2) Executing a trigger command.

       The write state is relatively  small,  on  the  order  of  hundreds  of  bytes  to  single
       kilobytes.  It  contains  information  on  the  number  of  completions  done,  the last X
       completions, etc.

       A trigger is invoked either through creation ('touch') of a specified file in the  system,
       or  through a timeout setting. If fio is run with `--trigger-file=/tmp/trigger-file', then
       it will continually check for the existence of  `/tmp/trigger-file'.  When  it  sees  this
       file, it will fire off the trigger (thus saving state, and executing the trigger command).

       For  client/server  runs,  there's both a local and remote trigger. If fio is running as a
       server backend, it will send the job states back to the  client  for  safe  storage,  then
       execute the remote trigger, if specified. If a local trigger is specified, the server will
       still send back the write state, but the client will then execute the trigger.

       Verification trigger example
              Let's say we want to run a powercut test on the remote Linux machine 'server'.  Our
              write  workload  is  in  `write-test.fio'. We want to cut power to 'server' at some
              point during the run, and we'll run this test from the safety or our local machine,
              'localbox'. On the server, we'll start the fio backend normally:

                     server# fio --server

              and on the client, we'll fire off the workload:

                     localbox$       fio      --client=server      --trigger-file=/tmp/my-trigger
                     --trigger-remote="bash -c "echo b > /proc/sysrq-triger""

              We set `/tmp/my-trigger' as the trigger file, and we tell fio to execute:

                     echo b > /proc/sysrq-trigger

              on the server once it has received the trigger and sent us the  write  state.  This
              will  work,  but  it's not really cutting power to the server, it's merely abruptly
              rebooting it. If we have a remote way of cutting power to the server  through  IPMI
              or  similar, we could do that through a local trigger command instead. Let's assume
              we have a script that does  IPMI  reboot  of  a  given  hostname,  ipmi-reboot.  On
              localbox, we could then have run fio with a local trigger instead:

                     localbox$       fio      --client=server      --trigger-file=/tmp/my-trigger
                     --trigger="ipmi-reboot server"

              For this case, fio would wait for the server to  send  us  the  write  state,  then
              execute `ipmi-reboot server' when that happened.

       Loading verify state
              To  load  stored  write  state,  a  read  verification  job  file  must contain the
              verify_state_load option. If that is set,  fio  will  load  the  previously  stored
              state.  For  a  local  fio run this is done by loading the files directly, and on a
              client/server run, the server backend will ask the client to send  the  files  over
              and load them from there.

LOG FILE FORMATS

       Fio  supports  a  variety of log file formats, for logging latencies, bandwidth, and IOPS.
       The logs share a common format, which looks like this:

              time (msec), value, data direction, block size  (bytes),  offset  (bytes),  command
              priority

       `Time' for the log entry is always in milliseconds. The `value' logged depends on the type
       of log, it will be one of the following:

              Latency log
                     Value is latency in nsecs

              Bandwidth log
                     Value is in KiB/sec

              IOPS log
                     Value is IOPS

       `Data direction' is one of the following:

              0      I/O is a READ

              1      I/O is a WRITE

              2      I/O is a TRIM

       The entry's `block size' is always in bytes. The `offset' is the position  in  bytes  from
       the  start  of  the file for that particular I/O. The logging of the offset can be toggled
       with log_offset.

       If log_prio is not set, the entry's `Command priority` is 1 for an IO  executed  with  the
       highest  RT  priority  class  (prioclass=1  or  cmdprio_class=1)  and 0 otherwise. This is
       controlled  by  the  prioclass  option  and  the  ioengine   specific   cmdprio_percentage
       cmdprio_class  options. If log_prio is set, the entry's `Command priority` is the priority
       set for the IO, as a 16-bits hexadecimal number with the lowest  13  bits  indicating  the
       priority  value  (prio  and  cmdprio  options)  and  the  highest 3 bits indicating the IO
       priority class (prioclass and cmdprio_class options).

       Fio defaults to logging every individual I/O but when  windowed  logging  is  set  through
       log_avg_msec,  either  the  average  (by  default)  or  the maximum (log_max_value is set)
       `value' seen over the specified period of time is recorded.  Each  `data  direction'  seen
       within  the window period will aggregate its values in a separate row. Further, when using
       windowed logging the `block size' and `offset' entries will always contain 0.

CLIENT / SERVER

       Normally fio is invoked as a stand-alone application on the machine where the I/O workload
       should  be generated. However, the backend and frontend of fio can be run separately i.e.,
       the fio server can generate an I/O  workload  on  the  "Device  Under  Test"  while  being
       controlled by a client on another machine.

       Start the server on the machine which has access to the storage DUT:

              $ fio --server=args

       where `args' defines what fio listens to. The arguments are of the form `type,hostname' or
       `IP,port'. `type' is either `ip' (or ip4) for TCP/IP v4, `ip6' for TCP/IP  v6,  or  `sock'
       for a local unix domain socket.  `hostname' is either a hostname or IP address, and `port'
       is the port to listen to (only valid for TCP/IP, not a local socket). Some examples:

              1) fio --server
                     Start a fio server, listening on all interfaces on the default port (8765).

              2) fio --server=ip:hostname,4444
                     Start a fio server, listening on IP belonging to hostname and on port 4444.

              3) fio --server=ip6:::1,4444
                     Start a fio server, listening on IPv6 localhost ::1 and on port 4444.

              4) fio --server=,4444
                     Start a fio server, listening on all interfaces on port 4444.

              5) fio --server=1.2.3.4
                     Start a fio server, listening on IP 1.2.3.4 on the default port.

              6) fio --server=sock:/tmp/fio.sock
                     Start a fio server, listening on the local socket `/tmp/fio.sock'.

       Once a server is running, a "client" can connect to the fio server with:

              $ fio <local-args> --client=<server> <remote-args> <job file(s)>

       where `local-args' are arguments for the client where  it  is  running,  `server'  is  the
       connect  string,  and `remote-args' and `job file(s)' are sent to the server. The `server'
       string follows the same format as it does on the server side, to allow  IP/hostname/socket
       and port strings.

       Fio can connect to multiple servers this way:

              $ fio --client=<server1> <job file(s)> --client=<server2> <job file(s)>

       If the job file is located on the fio server, then you can tell the server to load a local
       file as well. This is done by using --remote-config:

              $ fio --client=server --remote-config /path/to/file.fio

       Then fio will open this local (to the server) job file instead of being  passed  one  from
       the client.

       If you have many servers (example: 100 VMs/containers), you can input a pathname of a file
       containing host IPs/names as the parameter value for the  --client  option.  For  example,
       here is an example `host.list' file containing 2 hostnames:

              host1.your.dns.domain
              host2.your.dns.domain

       The fio command would then be:

              $ fio --client=host.list <job file(s)>

       In  this  mode,  you  cannot  input server-specific parameters or job files -- all servers
       receive the same job file.

       In order to let `fio --client' runs use a shared  filesystem  from  multiple  hosts,  `fio
       --client'  now  prepends the IP address of the server to the filename. For example, if fio
       is using the directory  `/mnt/nfs/fio'  and  is  writing  filename  `fileio.tmp',  with  a
       --client   `hostfile'   containing   two   hostnames  `h1'  and  `h2'  with  IP  addresses
       192.168.10.120 and 192.168.10.121, then fio will create two files:

              /mnt/nfs/fio/192.168.10.120.fileio.tmp
              /mnt/nfs/fio/192.168.10.121.fileio.tmp

       Terse output in client/server mode will differ slightly from what is produced when fio  is
       run in stand-alone mode. See the terse output section for details.

AUTHORS

       fio was written by Jens Axboe <axboe@kernel.dk>.
       This man page was written by Aaron Carroll <aaronc@cse.unsw.edu.au> based on documentation
       by Jens Axboe.
       This man page was rewritten by Tomohiro Kusumi <tkusumi@tuxera.com> based on documentation
       by Jens Axboe.

REPORTING BUGS

       Report bugs to the fio mailing list <fio@vger.kernel.org>.
       See REPORTING-BUGS.

       REPORTING-BUGS: http://git.kernel.dk/cgit/fio/plain/REPORTING-BUGS

SEE ALSO

       For further documentation see HOWTO and README.
       Sample jobfiles are available in the `examples/' directory.
       These are typically located under `/usr/share/doc/fio'.

       HOWTO: http://git.kernel.dk/cgit/fio/plain/HOWTO
       README: http://git.kernel.dk/cgit/fio/plain/README