Provided by: sg3-utils_1.33-1_amd64 bug


       sg3_utils - a package of utilities for sending SCSI commands


       sg_*  [--help]  [--hex]  [--maxlen=LEN]  [--raw]  [--verbose]  [--version] [OTHER_OPTIONS]


       sg3_utils is a package of utilities that send SCSI commands to the given DEVICE via a SCSI
       pass through interface provided by the host operating system.

       The names of all utilities start with "sg" and most start with "sg_" often followed by the
       name, or a shortening of the name, of the SCSI command that they  send.  For  example  the
       "sg_verify" utility sends the SCSI VERIFY command. A mapping between SCSI commands and the
       sg3_utils utilities that issue them is shown in the COVERAGE file.

       SCSI draft standards can be found at . The standards themselves can  be
       purchased  from  ANSI  and other standards organizations.  A good overview of various SCSI
       standards can be seen in with the SCSI command sets  in  the
       upper  part  of the diagram. SCSI commands in common with all device types can be found in
       SPC of which SPC-4 is the latest major version. Block device specific  commands  (e.g.  as
       used  by disks) are in SBC, those for tape drives in SSC and those for CD/DVD/BD drives in

       It is becoming more common to control ATA disks with the SCSI command set.  This  involves
       the  translation  of  SCSI commands to their corresponding ATA equivalents (and that is an
       imperfect mapping in some cases). The relevant standard is called SCSI to ATA  Translation
       (SAT  and  SAT-2  are  now  standards  at INCITS(ANSI) and ISO while SAT-3 is at the draft
       stage). The logic to perform the command translation is often called a SAT Layer  or  SATL
       and  may  be  within  an  operating system, in host bus adapter firmware or in an external
       device (e.g. associated with a SAS expander). See for more information.

       There is some support for SCSI tape devices but not for their basic commands.  The  reader
       is referred to the "mt" utility.

       There are two generations of command line option usage. The newer utilities (written since
       July 2004) use the getopt_long()  function  to  parse  command  line  options.  With  that
       function,  each option has two representations: a short form (e.g. '-v') and a longer form
       (e.g. '--verbose'). If an argument is required then it follows a space (optionally) in the
       short  form  and  a  "="  in  the longer form (e.g. in the sg_verify utility '-l 2a6h' and
       '--lba=2a6h' are equivalent). Note that with getopt_long(),  short  form  options  can  be
       elided,  for  example: '-all' is equivalent to '-a -l -l'.  The DEVICE argument may appear
       after, between or prior to any options.

       The older utilities, such as sg_inq, had individual command line processing code typically
       based on a single "-" followed by one or more characters. If an argument is needed then it
       follows a "=" (e.g. '-p=1f' in sg_modes with its older interface). Various options can  be
       elided as long as it is not ambiguous (e.g. '-vv' to increase the verbosity).

       Over  time the command line interface of these older utilities became messy and overloaded
       with options. So in sg3_utils version 1.23 the  command  line  interface  of  these  older
       utilities  was  altered  to  have  both  a cleaner getopt_long() interface and their older
       interface for  backward  compatibility.   By  default  these  older  utilities  use  their
       getopt_long()  based interface.  That can be overridden by defining the SG3_UTILS_OLD_OPTS
       environment variable or using '-O' or '--old' as the first command line  option.  The  man
       pages of the older utilities documents the details.

       Several  sg3_utils  utilities  are  based  on  the Unix dd command (e.g. sg_dd) and permit
       copying data at the level of SCSI READ and WRITE commands. sg_dd is tightly bound to Linux
       and  hence is not ported to other OSes. A more generic utility (than sg_dd) called ddpt in
       a package of the same name has been ported to other OSes.


       Normal disk block devices have names like /dev/sda, /dev/sdb, /dev/sdc, etc. SCSI disks in
       Linux  have always had names like that but in recent Linux kernels (e.g. lk 2.6 series) it
       is becoming more common for almost all disks to be named like that.  Partitions  within  a
       disk  are specified by a number appended to the device name, starting at 1 (e.g. /dev/sda1

       Tape  drives  are  named  /dev/st<num>  or  /dev/nst<num>  where  <num>  starts  at  zero.
       Additionally  one letter from this list: "lma" may be appended to the name. CD, DVD and BD
       readers (and writers) are named /dev/sr<num> where <num> start at  zero.  There  are  less
       used SCSI device type names, the dmesg and the lsscsi commands may help to find if any are
       attached to a running system.

       There is also a SCSI device driver which offers alternate generic access to SCSI  devices.
       It uses names of the form /dev/sg<num> where <num> starts at zero. The "lsscsi -g" command
       may be useful in finding these and which generic name corresponds to a  device  type  name
       (e.g.  /dev/sg2  may  correspond  to  /dev/sda). In the lk 2.6 series a block SCSI generic
       driver was introduced and its names are of the form /dev/bsg/<h:c:t:l> where h, c, t and l
       are  numbers.  Again  see  the lsscsi command to find the correspondence between that SCSI
       tuple (i.e. <h:c:t:l>) and alternate device names.

       Prior to the Linux kernel 2.6 series these utilities could only use generic  device  names
       (e.g.  /dev/sg1 ). In almost all cases in the Linux kernel 2.6 series, any device name can
       be used by these utilities.


       Storage and related devices can have several device names in Windows.  Probably  the  most
       common  in  the  volume  name  (e.g.  "D:"). There are also a "class" device names such as
       "PhysicalDrive<n>", "CDROM<n>" and "TAPE<n>". <n> is an integer starting at 0 allocated in
       ascending order as devices are discovered (and sometimes rediscovered).

       Some storage devices have a SCSI lower level device name which starts with a SCSI (pseudo)
       adapter name of the form "SCSI<n>:". To this is added sub-addressing  in  the  form  of  a
       "bus" number, a "target" identifier and a "lun" (logical unit number). The "bus" number is
       also known as a "PathId".  These are  assembled  to  form  a  device  name  of  the  form:
       "SCSI<n>:<bus>,<target>,<lun>".  The  trailing ",<lun>" may be omitted in which case a lun
       of zero is assumed. This lower level device name  cannot  often  be  used  directly  since
       Windows  blocks  attempts  to use it if a class driver has "claimed" the device. There are
       SCSI device types (e.g.  Automation/Drive interface type) for  which  there  is  no  class
       driver.  At least two transports ("bus types" in Windows jargon): USB and IEEE 1394 do not
       have a "scsi" device names of this form.

       In keeping with DOS file system conventions, the various device  names  can  be  given  in
       upper, lower or mixed case. Since "PhysicalDrive<n>" is tedious to write, a shortened form
       of "PD<n>" is permitted by all utilities in this package.

       A single device (e.g. a disk) can have many device names. For example: "PD0" can  also  be
       "C:",  "D:"  and  "SCSI0:0,1,0".  The  two  volume  names  reflect  that  the disk has two
       partitions on it. Disk partitions that are not recognised by Windows are not usually given
       a  volume  name.  However Vista does show a volume name for a disk which has no partitions
       recognised by it and when selected invites the user to format  it  (which  may  be  rather
       unfriendly to other OSes).

       These utilities assume a given device name is in the Win32 device namespace.  To make that
       explicit "\\.\" can be prepended to the device names mentioned  in  this  section.  Beware
       that  backslash is an escape character in Unix like shells and the C programming language.
       In a shell like Msys (from MinGW) each backslash may need to be typed twice.

       The sg_scan utility within this package lists out Windows device names in a form  that  is
       suitable for other utilities in this package to use.


       SCSI disks have block names of the form /dev/da<num> where <num> is an integer starting at
       zero. The "da" is replaced by "sa" for SCSI  tape  drives  and  "cd"  for  SCSI  CD/DVD/BD
       drives.  Each  SCSI  device  has  a  corresponding  pass-through  device  name of the form
       /dev/pass<num> where <num> is an  integer  starting  at  zero.  The  "camcontrol  devlist"
       command  may  be  useful  for  finding  out  which SCSI device names are available and the
       correspondence between between class and pass-through names.


       SCSI device names below the /dev directory have a form like:  c5t4d3s2  where  the  number
       following  "c"  is  the  controller  (HBA)  number, the number following "t" is the target
       number (from the SCSI parallel interface days) and the number following "d"  is  the  LUN.
       Following  the  "s"  is the slice number which is related to a partition and by convention
       "s2" is the whole disk.

       OpenSolaris also has a c5t4d3p2 form where the number following the "p" is  the  partition
       number  apart  from  "p0"  which  is the whole disk. So a whole disk may be referred to as
       either c5t4d3, c5t4d3s2 or c5t4d3p0 .

       And these device names are duplicated in  the  /dev/dsk  and  /dev/rdsk  directories.  The
       former  is the block device name and the latter is for "raw" (or char device) access which
       is  what  sg3_utils  needs.  So   in   OpenSolaris   something   of   the   form   'sg_inq
       /dev/rdsk/c5t4d3p0'  should  work.   If  it doesn't work then add a '-vvv' option for more
       debug information.  Trying this form 'sg_inq /dev/dsk/c5t4d3p0' (note  "rdsk"  changed  to
       "dsk") will result in an "inappropriate ioctl for device" error.

       The  device  names  within  the /dev directory are typically symbolic links to much longer
       topological names in the /device directory. In Solaris cd/dvd/bd drives seem to be treated
       as  disks  and so are found in the /dev/rdsk directory. Tape drives appear in the /dev/rmt

       There is also a sgen (SCSI generic) driver which by default does not attach to any device.
       See  the  /kernel/drv/sgen.conf file to control what is attached. Any attached device will
       have a device name of the form /dev/scsi/c5t4d3 .

       Listing available SCSI devices in Solaris seems to  be  a  challenge.  "Use  the  'format'
       command"  advice  works  but  seems  a very dangerous way to list devices. [It does prompt
       again before doing any damage.] 'devfsadm -Cv' cleans out the  clutter  in  the  /dev/rdsk
       directory, only leaving what is "live". The "cfgadm -v" command looks promising.


       To  aid  scripts that call these utilities, the exit status is set to indicate success (0)
       or failure (1 or more). Note that some of the lower values correspond to  the  SCSI  sense
       key values. The exit status values are:

       0      success

       1      syntax  error. Either illegal command line options, options with bad arguments or a
              combination of options that is not permitted.

       2      the DEVICE reports that it is not ready for the operation requested. The device may
              be  in  the  process  of becoming ready (e.g.  spinning up but not at speed) so the
              utility may work after a wait.

       3      the DEVICE reports a medium or hardware error (or a blank check).  For  example  an
              attempt to read a corrupted block on a disk will yield this value.

       5      the  DEVICE  reports  an "illegal request" with an additional sense code other than
              "invalid command operation code". This is often a supported command  with  a  field
              set  requesting  an  unsupported  capability.  For commands that require a "service
              action" field this value can indicate that the command  with  that  service  action
              value is not supported.

       6      the  DEVICE  reports  a  "unit  attention"  condition.  This usually indicates that
              something unrelated to the requested command has occurred  (e.g.  a  device  reset)
              potentially before the current SCSI command was sent. The requested command has not
              been executed by the device. Note that unit attention conditions are  usually  only
              reported once by a device.

       9      the  DEVICE  reports  an  illegal request with an additional sense code of "invalid
              command operation code" which means that it doesn't support the requested command.

       11     the DEVICE reports an aborted command.  In  some  cases  aborted  commands  can  be
              retried immediately (e.g. if the transport aborted the command due to congestion).

       15     the  utility is unable to open, close or use the given DEVICE.  The given file name
              could be incorrect or there may be permission problems. Adding the '-v' option  may
              give more information.

       20     the DEVICE reports it has a check condition but "no sense" and non-zero information
              in its additional sense codes. Some  polling  commands  (e.g.  REQUEST  SENSE)  can
              receive this response.

       21     the  DEVICE reports a "recovered error". The requested command was successful. Most
              likely a utility will report a recovered error to  stderr  and  continue,  probably
              leaving the utility with an exit status of 0 .

       33     the command sent to DEVICE has timed out.

       97     the response to a SCSI command failed sanity checks.

       98     the  DEVICE  reports it has a check condition but the error doesn't fit into any of
              the above categories.

       99     any errors that can't be categorized into values 1 to 98 may yield this value. This
              includes  transport  and operating system errors after the command has been sent to
              the device.

       Most of the error conditions reported above will be repeatable (an example of one that  is
       not is "unit attention") so the utility can be run again with the '-v' option (or several)
       to obtain more information.


       Arguments to long options are mandatory for short options as well. In the  short  form  an
       argument  to  an  option uses zero or more spaces as a separator (i.e. the short form does
       not use "=" as a separator).

       If an option takes a numeric argument then that argument is assumed to be  decimal  unless
       otherwise  indicated  (e.g.  with  a leading "0x", a trailing "h" or as noted in the usage

       Some options are used uniformally in most of the utilities in this package. Those  options
       are listed below. Note that there are some exceptions.

       -h, -?, --help
              output  the  usage  message  then  exit.  In  a few older utilities the '-h' option
              requests hexadecimal output. In these cases the '-?' option will output  the  usage
              message then exit.

       -H, --hex
              for  SCSI  commands  that  yield a non-trivial response, print out that response in
              ASCII hexadecimal.

       -m, --maxlen=LEN
              several important SCSI commands (e.g. INQUIRY and MODE SENSE) have response lengths
              that  vary  depending on many factors, only some of which these utilities take into
              account. The maximum response length is  typically  specified  in  the  'allocation
              length'  field  of  the cdb. In the absence of this option, several utilities use a
              default allocation length (sometimes recommended in the SCSI draft standards) or  a
              "double  fetch"  strategy.   See sg_logs(8) for its description of a "double fetch"
              strategy. These techniques are imperfect and in the presence of faulty SCSI targets
              can  cause  problems  (e.g. some USB mass storage devices freeze if they receive an
              INQUIRY allocation length other than 36). Also use  of  this  option  disables  any
              "double fetch" strategy that may have otherwise been used.

       -r, --raw
              for SCSI commands that yield a non-trivial response, output that response in binary
              to stdout. If any error messages or warning are produced they are usually  sent  to
              stderr.  Some utilities that consume data to send to the device along with the SCSI
              command, use this option to provide that data or indicate that it can be read  from

       -v, --verbose
              increase the level of verbosity, (i.e. debug output). Can be used multiple times to
              further increase verbosity. The additional output is usually sent to stderr.

       -V, --version
              print the version string and then exit. Each utility has its own version number and
              date of last code change.


       Many  utilities  have  command  line  options  that  take numeric arguments. These numeric
       arguments can be large values (e.g. a logical block address (LBA) on a disk)  and  can  be
       inconvenient   to   enter   in  the  default  decimal  representation.  So  various  other
       representations are permitted.

       Multiplicative suffixes are accepted. They are one, two or three letter  strings  appended
       directly after the number to which they apply:

          c C         *1
          w W         *2
          b B         *512
          k K KiB     *1024
          KB          *1000
          m M MiB     *1048576
          MB          *1000000
          g G GiB     *(2^30)
          GB          *(10^9)
          t T TiB     *(2^40)
          TB          *(10^12)
          p P PiB     *(2^50)
          PB          *(10^15)

       An  example  is  "2k"  for  2048.  The large tera and peta suffixes are only available for
       numeric arguments that might require 64 bits to represent internally.

       A suffix of the form "x<n>" multiplies the leading number by <n>. An example is "2x33" for
       "66".  The  leading  number  cannot  be  "0"  (zero)  as  that  would  be interpreted as a
       hexadecimal number (see below).

       These multiplicative suffixes are compatible with GNU's  dd  command  (since  2002)  which
       claims compliance with SI and with IEC 60027-2.

       Alternatively numerical arguments can be given in hexadecimal. There are two syntaxes. The
       number can be preceded by either "0x" or "0X" as found in the C programming language.  The
       second  hexadecimal  representation  is  a  trailing  "h"  or  "H"  as  found in (storage)
       standards. When hex numbers are given, multipliers cannot be used. For example the decimal
       value "256" can be given as "0x100" or "100h".


       There  are several Bourne shell scripts in the 'scripts' subdirectory that invoke compiled
       utilities (e.g. sg_readcap). The scripts start with 'scsi_' rather than 'sg_'. One purpose
       of  these scripts is to call the same utility (e.g. sg_readcap) on multiple disks. Most of
       the basic compiled utilities only allow one device  as  an  argument.  Some  distributions
       install  these  scripts  in a visible directory (e.g. /usr/src/bin). Some of these scripts
       have man page entries. See the README file in the 'scripts' subdirectory.

       There is some example C code plus  examples  of  complex  invocations  in  the  'examples'
       subdirectory.  There  is also a README file. The example C may be a simpler example of how
       to use a SCSI  pass-through  in  Linux  than  the  main  utilities  (found  in  the  'src'
       subdirectory).  This  is  due  to  the fewer abstraction layers (e.g. they don't worry the
       MinGW in Windows may open a file in text rather than binary mode).

       Some utilities that  the  author  has  found  useful  have  been  placed  in  the  'utils'


       There  is a web page discussing this package at . The
       device naming used by this package on various operating system is discussed in  the  page: .


       Written by Douglas Gilbert. Some utilities have been contributed, see the CREDITS file and
       individual source files (in the 'src' directory).


       Report bugs to <dgilbert at interlog dot com>.


       Copyright © 1999-2012 Douglas Gilbert
       Some utilities are distributed under a GPL version 2 license while  others,  usually  more
       recent  ones,  are  under  a  FreeBSD  license.  The  files  that are common to almost all
       utilities and thus contain the most reusable code, namely sg_lib.[hc],  sg_cmds_basic.[hc]
       and  sg_cmds_extra.[hc]  are  under  a FreeBSD license. There is NO warranty; not even for


       sdparm(sdparm), ddpt(ddpt), lsscsi(lsscsi), dmesg(1), mt(1)