Provided by: fio_3.28-1_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=jobfile
              Convert jobfile 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
              Tell fio to terminate processing after the specified period  of  time.  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
              When running a random write test across an entire drive many  more  zones  will  be
              open  than  in  a typical application workload. Hence this command line option that
              allows to limit the number of open zones. The number of open zones  is  defined  as
              the number of zones to which write commands are issued by all threads/processes.

       job_max_open_zones=int
              Limit on the number of simultaneously opened zones per single thread/process.

       ignore_zone_limits=bool
              If  this  isn't  set,  fio will query the max open zones limit from the zoned block
              device, and exit if the specified max_open_zones value is  larger  than  the  limit
              reported by the device. Default: false.

       zone_reset_threshold=float
              A  number between zero and one that indicates the ratio of logical blocks with data
              to the total number of logical blocks in the test above which zones should be reset
              periodically.

       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.

       atomic=bool
              If value is true, attempt to use atomic direct I/O. Atomic writes are guaranteed to
              be  stable  once acknowledged by the operating system. Only Linux supports O_ATOMIC
              right now.

       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.

              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, you would get a  new
              random  offset  for every 8 I/Os. The result would be a seek for only every 8 I/Os,
              instead of for every I/O. Use `rw=randread:8' to specify that. As sequential I/O is
              already   sequential,   setting  sequential  for  that  would  not  result  in  any
              differences. identical behaves in a similar  fashion,  except  it  sends  the  same
              offset 8 number of times before generating a new offset.

       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 the random number generator used for random I/O patterns in a predictable  way
              so the pattern is repeatable across runs. Default: true.

       allrandrepeat=bool
              Seed  all  random  number generators in a predictable way so results are repeatable
              across runs. Default: false.

       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.

       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,  FreeBSD,  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 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_distibution=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

       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 4MiB in size. 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'.  Defaults  to  4MiB.  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 limited by other options (such
              as runtime, for instance, or increased/decreased by io_size).  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 and limited to size in  total  (if  that  is
              given).  If  not  given, each created file is the same size.  This option overrides
              size in terms of file size, which means this value is  used  as  a  fixed  size  or
              possible range of each file.

       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.

                     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.

                     pmemblk
                            Read and write using filesystem DAX to a file on a filesystem mounted
                            with  DAX  on  a persistent memory device through the PMDK libpmemblk
                            library.

                     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.

   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.  This  option cannot be used with the `prio` or
              `prioclass` options. 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.

       (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 format for this
              option is the same as the format of the bssplit option,  with  the  exception  that
              values  for  trim  IOs  are  ignored.  This  option  is mutually exclusive with the
              cmdprio_percentage option.

       (io_uring)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)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)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)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.

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

       (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)nowait
              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.

       (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)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.

       (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_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 three values:

                     write (default)
                            Write opcodes are issued as usual

                     verify Issue  WRITE  AND  VERIFY  commands. The BYTCHK bit is set to 0. This
                            directs the device to carry out a medium verification  with  no  data
                            comparison. The writefua option is ignored with this selection.

                     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.

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

       (dfs)object_class
              Specificy  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=ool
              If set, stdout and stderr streams are redirected to files named from the job  name.
              Default is true.

   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.

   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.

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

   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.

       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
              muliple 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.

       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.

       experimental_verify=bool
              Enable experimental verification.

   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 once per second. 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.

   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_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.

       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.  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 samples. 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 samples. Same names as bw.

              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 to access more then 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.

                            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.

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