Go to main content

man pages section 8: System Administration Commands

Exit Print View

Updated: Thursday, June 13, 2019

sg_format (8)


sg_format - format, resize a SCSI disk or format a tape


sg_format    [--cmplst={0|1}]    [--count=COUNT]   [--dcrt]   [--early]
[--ffmy=FFMT] [--fmtpinfo=FPI] [--format] [--help] [--ip_def]  [--long]
[--mode=MP]  [--pfu=PFU]  [--pie=PIE]  [--pinfo] [--poll=PT] [--resize]
[--rto_req] [--security] [--six] [--size=SIZE] [--tape=FM]  [--verbose]
[--verify] [--version] [--wait] DEVICE


SG_FORMAT(8)                       SG3_UTILS                      SG_FORMAT(8)

       sg_format - format, resize a SCSI disk or format a tape

       sg_format    [--cmplst={0|1}]    [--count=COUNT]   [--dcrt]   [--early]
       [--ffmy=FFMT] [--fmtpinfo=FPI] [--format] [--help] [--ip_def]  [--long]
       [--mode=MP]  [--pfu=PFU]  [--pie=PIE]  [--pinfo] [--poll=PT] [--resize]
       [--rto_req] [--security] [--six] [--size=SIZE] [--tape=FM]  [--verbose]
       [--verify] [--version] [--wait] DEVICE

       Not  all  SCSI direct access devices need to be formatted and some have
       vendor specific formatting procedures. SCSI disks with  rotating  media
       are  probably  the  largest  group  that do support a 'standard' format
       operation. They are typically factory formatted to a block size of  512
       bytes  with  the  largest number of blocks that the manufacturer recom-
       mends. The manufacturer's recommendation typically leaves aside a  cer-
       tain  number  of  tracks,  spread across the media, for reassignment of
       blocks to logical block addresses during the life of the disk.

       This utility can format modern SCSI disks and potentially change  their
       block  size (if permitted) and the block count (i.e. number of accessi-
       ble blocks on the media also known as "resizing"). Resizing a  disk  to
       less  than  the  manufacturer's  recommended  block  count is sometimes
       called "short stroking" (see NOTES section). Resizing the  block  count
       while  not  changing the block size may not require a format operation.
       The SBC-2 standard (see www.t10.org) has obsoleted the "format  device"
       mode  page.  Many  of the low level details found in that mode page are
       now left up to the discretion of the manufacturer.

       When this utility is used without options (i.e.  it  is  only  given  a
       DEVICE  argument) it prints out the existing block size and block count
       derived from two sources. These two sources are a block  descriptor  in
       the  response to a MODE SENSE command and the response to a READ CAPAC-
       ITY command.  The reason for this double check is to detect  a  "format
       corrupt"  state (see the NOTES section). This usage will not modify the

       When this utility is used with the "--format" (or "-F") option it  will
       attempt  to  format the given DEVICE. There is a 15 second pause during
       which time the user is  invited  thrice  (5  seconds  apart)  to  abort
       sg_format.  This  occurs  just prior the SCSI FORMAT UNIT command being
       issued. See the NOTES section for more information.

       Protection information is optional and is made up of one or  more  pro-
       tection intervals, each made up of 8 bytes associated with each logical
       block. Four protection types are defined with protection type  0  being
       no  protection  intervals. See the PROTECTION INFORMATION section below
       for more information.

       When the --tape=FM option is given then the SCSI FORMAT MEDIUM  command
       is  sent  to the DEVICE. FORMAT MEDIUM is defined in SSC and prepares a
       volume for use which may include partitioning the medium. See the  sec-
       tion below on TAPE for more information.

       Arguments to long options are mandatory for short options as well.  The
       options are arranged in alphabetical order based  on  the  long  option

       -C, --cmplst={0|1}
              sets  the CMPLST ("complete list") bit in the FORMAT UNIT cdb to
              0 or 1.  The default is 1  in  which  case  the  existing  GLIST
              (grown  list)  is  ignored.  If the value is 0 then the existing
              GLIST is taken into account. See the  LISTS  section  below.  In
              most cases this bit should be left set; some MO disk drives need
              this bit cleared.

       -c, --count=COUNT
              where COUNT is the number of blocks to be formatted or media  to
              be  resized  to.  Can  be used with either --format or --resize.
              With --format this option need not be given in which case it  is
              assumed  to  be  zero. With --format the interpretation of COUNT
                (COUNT > 0) : only format the first COUNT blocks and READ
                              CAPACITY will report COUNT blocks after format
                (COUNT = 0) and block size  unchanged  :  use  existing  block
                (COUNT = 0) and block size changed : recommended maximum block
                                                     count for new block size
                (COUNT = -1) : use recommended maximum block count
                (COUNT < -1) : illegal
              With  --resize  this  option  must  be  given and COUNT has this
                (COUNT > 0) : after resize READ CAPACITY will report COUNT
                (COUNT = 0) : after resize READ CAPACITY will report 0 blocks
                (COUNT = -1) : after resize READ CAPACITY will report its
                               maximum number of blocks
                (COUNT < -1) : illegal
              In both cases if the given COUNT exceeds the maximum  number  of
              blocks (for the block size) then the disk reports an error.  See
              NOTES section below.

       -D, --dcrt
              this option sets the DCRT  bit  in  the  FORMAT  UNIT  command's
              parameter list header. It will "disable certification". Certifi-
              cation  verifies  that  blocks  are  usable  during  the  format
              process.  Using  this  option may speed the format.  The default
              action of this utility (i.e. when this option is not  given)  is
              to  clear the DCRT bit thereby requesting "media certification".
              When the DCRT bit is set, the FOV bit must  also  be  set  hence
              sg_format does that.

       -e, --early
              during a format operation, The default action of this utility is
              to poll the disk every 60 seconds to determine the  progress  of
              the  format  operation until it is finished. When this option is
              given this utility will exit "early", that is  as  soon  as  the
              format  operation  has  commenced. Then the user can monitor the
              progress of the ongoing format operation  with  other  utilities
              (e.g.  sg_turs(8) or sg_requests(8)). This option and --wait are
              mutually exclusive.

       -t, --ffmt=FFMT
              FFMT is placed in a field of the same name in  the  FORMAT  UNIT
              cdb.  The field was introduced in SBC-4 revision 10. The default
              value is 0 which implies the former action to typically write to
              all blocks on the DEVICE and that can take a long time.
              FFMT  has  values  1 and 2 for fast format with 3 being reserved
              currently. The difference between 1 and 2 concerns  read  opera-
              tions  on  LBAs  to which no data has been written to, since the
              fast format. When FFMT is 1 the  read  operation  should  return
              "unspecified  logical  block  data"  and complete without error.
              When FFMT is 2 the read operation should yield  check  condition
              status  with  a sense key set to hardware error, medium error or
              command aborted. See SBC-4 revsion  10  section  4.35  for  more

       -f, --fmtpinfo=FPI
              sets  the  FMTPINFO  field  in  the  FORMAT  UNIT cdb to a value
              between 0 and 3.  The default value is  0.  The  FMTPINFO  field
              from  SBC-3 revision 16 is a 2 bit field (bits 7 and 6 of byte 1
              in the cdb). Prior to that it was a single bit field (bit  7  of
              byte  1  in  the  cdb)  and there was an accompanying bit called
              RTO_REQ (bit 6 of byte 1 in the  cdb).  The  deprecated  options
              "--pinfo" and "--rto-req" represent the older usage. This option
              should be used in their place. See  the  PROTECTION  INFORMATION
              section below for more information.

       -F, --format
              issue  a  SCSI  FORMAT  UNIT command.  This will destroy all the
              data held on the media.  This option is required to  change  the
              block  size  of a disk. The user is given a 15 second count down
              to ponder the wisdom of doing this, during which time  control-C
              (amongst  other  Unix commands) can be used to kill this process
              before it does any damage.
              When used three times (or more) the preliminary MODE  SENSE  and
              SELECT  commands  are bypassed, leaving only the initial INQUIRY
              and FORMAT UNIT commands. This is for emergency use  (e.g.  when
              the  MODE  SENSE/SELECT  commands  are  not  working) and cannot
              change the logical block size.
              See NOTES section for implementation details and  EXAMPLES  sec-
              tion for typical use.

       -h, --help
              print out the usage information then exit.

       -I, --ip_def
              sets  the  default Initialization Pattern. Some disks (SSDs) use
              this to flag that a format should fully  provision  (i.e.  asso-
              ciate a physical block with every logical block). The same disks
              (SSDs) might thin provision if this option is not given. If this
              option is given then the --security option cannot be given.

       -l, --long
              the  default  action of this utility is to assume 32 bit logical
              block addresses. With 512 byte block size this permits more than
              2 terabytes (almost 2 ** 41 bytes) on a single disk. This option
              selects commands and parameters that allow for  64  bit  logical
              block  addresses.   Specifically  this option sets the "longlba"
              flag in the MODE SENSE (10) command and uses READ CAPACITY  (16)
              rather  than READ CAPACITY (10). If this option is not given and
              READ CAPACITY (10) or MODE SELECT detects a disk the needs  more
              than  32  bits  to  represent  its logical blocks then it is set
              internally. This option does not set the  LONGLIST  bit  in  the
              FORMAT UNIT command. The LONGLIST bit is set as required depend-
              ing other parameters (e.g.  when  '--pie=PIE'  is  greater  than

       -M, --mode=MP
              MP  is  a mode page number (0 to 62 inclusive) that will be used
              for reading and perhaps changing the device logical block  size.
              The  default  is  1  which is the Read-Write Error Recovery mode

       -P, --pfu=PFU
              sets the "Protection Field Usage" field in the  parameter  block
              associated  with a FORMAT UNIT command to PFU. The default value
              is 0, the only other defined value currently is 1. See the  PRO-
              TECTION INFORMATION section below for more information.

       -q, --pie=PIE
              sets  the  "Protection Interval Exponent" field in the parameter
              block associated with a FORMAT UNIT command to PIE. The  default
              value  is  0.   PIE can only be non-zero with protection types 2
              and 3.  The value of 0 is typical for 512 byte blocks; with 4096
              byte  blocks  a value of 3 may be appropriate (i.e. 8 protection
              intervals interleaved with 4096 bytes of user  data).  A  device
              may  not  support any non-zero values. This field first appeared
              in SBC-3 revision 18.

       -p, --pinfo
              this  option  is  deprecated,  use  the  --fmtpinfo=FPI   option
              instead.   If  used,  then it sets bit 7 of byte 1 in the FORMAT
              UNIT cdb and that is equivalent to setting --fmtpinfo=2. [So  if
              --pinfo is used (plus --fmtpinfo=FPI and --pfu=PFU are not given
              or their arguments are 0) then protection type 1 is selected.]

       -x, --poll=PT
              where PT is the type of poll used. If PT is 0 then a  TEST  UNIT
              READY  command  is  used,  otherwise  a REQUEST SENSE command is
              used. The default is currently 0 but this will change  to  1  in
              the near future. See the NOTES sections below.

       -r, --resize
              rather  than  format  the  disk,  it  can be resized. This means
              changing the number of blocks on the device reported by the READ
              CAPACITY   command.    This  option  should  be  used  with  the
              --count=COUNT option.  The contents of all logical blocks on the
              media remain unchanged when this option is used. This means that
              any resize operation can be reversed. This option cannot be used
              together with either --format or a --size=SIZE whose argument is
              different to the existing block size.

       -R, --rto_req
              The option is deprecated, use the --fmtpinfo=FPI option instead.
              If used, then it sets bit 6 of byte 1 in the FORMAT UNIT cdb.

       -S, --security
              sets  the  "Security Initialization" (SI) bit in the FORMAT UNIT
              command's initialization pattern descriptor within the parameter
              list.  According  to  SBC-3  the  default initialization pattern
              "shall be written using a security erasure write technique". See
              the  NOTES  section on the SCSI SANITIZE command. If this option
              is given then the --ip_def option cannot be given.

       -6, --six
              Use 6 byte variants of MODE SENSE and MODE SELECT.  The  default
              action  is to use the 10 byte variants. Some MO drives need this
              option set when doing a format.

       -s, --size=SIZE
              where SIZE is the block size  (i.e.  number  of  bytes  in  each
              block) to format the device to. The default value is whatever is
              currently reported by the block descriptor in a MODE SENSE  com-
              mand.  If  the block size given by this option is different from
              the current value then a MODE SELECT command is used  to  change
              it  prior  to  the  FORMAT UNIT command being started (as recom-
              mended in the draft standard). Many SCSI  disks  have  512  byte
              sectors  by  default  and allow up to 16 bytes extra in a sector
              (i.e. 528 byte sectors).  If the given size in unacceptable with
              the  disk, most likely an "Invalid field in parameter list" mes-
              sage will appear in sense data (requires  the  use  of  '-v'  to
              decode sense data).

       -T, --tape=FM
              will  send a FORMAT MEDIUM command to the DEVICE with the FORMAT
              field set to FM. This option is used to prepare a tape (i.e. the
              "medium") in a tape drive for use. Values for FM include 0 to do
              the "default" format; 1 to partition a volume  and  2  to  do  a
              default format then partition.

       -v, --verbose
              increase  the  level  of  verbosity, (i.e. debug output). "-vvv"
              gives a lot more debug output.

       -y, --verify
              set the VERIFY bit in the FORMAT MEDIUM cdb. The default is that
              the  VERIFY  bit  is  clear. This option is only appropriate for

       -V, --version
              print the version string and then exit.

       -w, --wait
              the default format action is to set the "IMMED" bit in the  FOR-
              MAT  UNIT  command's  (short)  parameter  header. If this option
              (i.e. --wait) is given then the  "IMMED"  bit  is  not  set.  If
              --wait  is  given the FORMAT UNIT command waits until the format
              operation completes before returning its response. This  can  be
              many  hours  on large disks. This utility sets a 15 hour timeout
              on such a FORMAT UNIT command! Some recent SSDs go to the  other
              extreme  of  completing  a format operation in 1.5 seconds hence
              waiting is not an issue.

       The SBC-3 draft (revision 36) defines PLIST, CLIST, DLIST and GLIST  in
       section  4.13  on "Medium defects". Briefly, the PLIST is the "primary"
       list of manufacturer detected defects, the CLIST ("certification" list)
       contains  those  detected  during  the format operation, the DLIST is a
       list of defects that can be given to the format operation. The GLIST is
       the  grown  list  which starts in the format process as CLIST+DLIST and
       can "grow" later due to automatic reallocation (see the ARRE  and  AWRE
       bits  in  the  Read-Write Error Recovery mode page (see sdparm(8))) and
       use of the SCSI REASSIGN BLOCKS command (see sg_reassign(8)).

       The CMPLST bit  (controlled  by  the  --cmplst=0|1  option)  determines
       whether  the  existing  GLIST, when the format operation is invoked, is
       taken into account. The sg_format utility sets  the  FOV  bit  to  zero
       which causes DPRY=0, so the PLIST is taken into account, and DCRT=0, so
       the CLIST is generated and used during the format process.

       The sg_format utility does not permit a user to provide a  defect  list
       (i.e. DLIST).

       Protection Information (PI) is additional information held with logical
       blocks so that an application and/or host bus  adapter  can  check  the
       correctness  of  those logical blocks. PI is placed in one or more pro-
       tection intervals beside each logical block. A protection interval con-
       tains 8 bytes made up of a 2 byte "logical block guard" (CRC), a 2 byte
       "logical block application guard", and a 4 byte "logical  block  refer-
       ence  tag". Devices with 512 byte logical block size typically have one
       protection interval appended, making its logical block data  520  bytes
       long. Devices with 4096 byte logical block size often have 8 protection
       intervals spread across its logical block data for a total size of 4160
       bytes.  Note that for all other purposes the logical block size is con-
       sidered to be 512 and 4096 bytes respectively.

       SBC-3 drafts have added several "protection types" to the PI introduced
       in  the SBC-2 standard. SBC-3 defines 4 protection types (types 0 to 3)
       with protection type 0 meaning no PI is maintained. While a device  may
       support  one  or more protection types, it can only be formatted with 1
       of the 4. To change a device's protection type, it must  be  re-format-
       ted.  For  more  information  see the Protection Information in section
       4.22 of draft SBC-3 revision 36.

       A device that supports PI information (i.e. supports one or  more  pro-
       tection  types  1,  2  and  3)  sets  the "PROTECT" bit in its standard
       INQUIRY response. It also sets the SPT field in  the  EXTENDED  INQUIRY
       VPD page response to indicate which protection types it supports. Given
       PROTECT=1 then SPT=0 implies the device supports PI type 1 only,  SPT=1
       implies  the  device  supports  PI  types  1  and  2, and various other
       non-obvious mappings up to SPT=7 which implies protection  types  1,  2
       and 3 are supported. The current protection type of a disk can be found
       in the "P_TYPE" and "PROT_EN" fields in the response of a READ CAPACITY
       (16) command (e.g. with the 'sg_readcap --long' utility).

       Given  that  a device supports a particular protection type, a user can
       then choose to format that disk with that protection  type  by  setting
       the  "FMTPINFO"  and "Protection Field Usage" fields in the FORMAT UNIT
       command.  Those  fields  correspond  to  the  --fmtpinfo=FPI  and   the
       --pfu=PFU  options  in this utility. The list below shows the four pro-
       tection types followed by the options of this utility needed to  select
         0 : --fmtpinfo=0 --pfu=0
         1 : --fmtpinfo=2 --pfu=0
         2 : --fmtpinfo=3 --pfu=0
         3 : --fmtpinfo=3 --pfu=1
       The default value of FPI (in --fmtpinfo=FPI) is 0 and the default value
       of PFU (in --pfu=PFU) is 0. So if neither --fmtpinfo=FPI nor  --pfu=PFU
       are  given  then  protection type 0 (i.e. no protection information) is

       See attributes(7) for descriptions of the following attributes:

       |Availability   | system/storage/sg3_utils |
       |Stability      | Pass-through uncommitted |
       The SBC-2 standard states that the REQUEST SENSE command should be used
       for  obtaining progress indication when the format command is underway.
       However, tests on a selection of disks shows that TEST UNIT READY  com-
       mands  yield  progress indications (but not REQUEST SENSE commands). So
       the current version of this utility defaults to using TEST  UNIT  READY
       commands  to  poll the disk to find out the progress of the format. The
       --poll=PT option has been added to control this.

       When the --format option is given without the --wait  option  then  the
       SCSI  FORMAT UNIT command is issued with the IMMED bit set which causes
       the SCSI command to return after it has started the  format  operation.
       The  --early option will cause sg_format to exit at that point.  Other-
       wise the DEVICE is polled every 60 seconds  with  TEST  UNIT  READY  or
       REQUEST SENSE commands until it reports an "all clear" (i.e. the format
       operation has completed). Normally these polling commands  will  result
       in a progress indicator (expressed as a percentage) being output to the
       screen.  If the user gets  bored  watching  the  progress  report  then
       sg_format  process  can  be  terminated  (e.g.  with control-C) without
       affecting the format operation which continues.  However  a  target  or
       device  reset  (or  a  power  cycle)  will probably cause the device to
       become "format corrupt".

       When the --format and --wait options are both given then  this  utility
       may  take  a long time to return. In this case care should be taken not
       to send any other SCSI commands to the disk as it may not respond leav-
       ing  those  commands  queued behind the active format command. This may
       cause a timeout in the OS driver (in a lot shorter period than 15 hours
       applicable to some format operations). This may result in the OS reset-
       ting the disk leaving the format operation incomplete. This  may  leave
       the disk in a "format corrupt" state requiring another format to remedy
       the situation.

       When the block size (i.e. the number of bytes in each block) is changed
       on  a  disk two SCSI commands must be sent: a MODE SELECT to change the
       block size followed by a FORMAT command. If  the  MODE  SELECT  command
       succeeds  and the FORMAT fails then the disk may be in a state that the
       draft standard calls "format corrupt". A block descriptor in  a  subse-
       quent  MODE SENSE will report the requested new block size while a READ
       CAPACITY command will report the existing (i.e. different) block  size.
       Alternatively  the READ CAPACITY command may fail, reporting the device
       is not ready, potentially requiring a format. The solution to this sit-
       uation  is  to do a format again (and this time the new block size does
       not have to be given) or change the block size  back  to  the  original

       The  SBC-2  standard states that the block count can be set back to the
       manufacturer's maximum recommended value in a format or  resize  opera-
       tion.   This can be done by placing an address of 0xffffffff (or the 64
       bit equivalent) in the appropriate block descriptor  field  to  a  MODE
       SELECT command. In signed (two's complement) arithmetic that value cor-
       responds to  the  manufacturer's  maximum  recommended  value.  To  see
       exactly  which  SCSI  commands are being executed and parameters passed
       add the "-vvv" option to the sg_format command line.

       Short stroking is a technique to trade off  capacity  for  performance.
       Rotating  disk performance is usually highest on the outer tracks (i.e.
       lower logical block addresses) so by resizing or reformatting a disk to
       a smaller capacity, average performance will usually be increased.

       Other  utilities  may  be useful in finding information associated with
       formatting. These include sg_inq(8) to fetch standard INQUIRY  informa-
       tion  (e.g. the PROTECT bit) and to fetch the EXTENDED INQUIRY VPD page
       (e.g. RTO and GRD_CHK bits). The  sdparm(8)  utility  can  be  used  to
       access and potentially change the now obsolete format mode page.

       scsiformat  is another utility available for formatting SCSI disks with
       Linux. It dates from 1997 (most recent update) and may  be  useful  for
       disks whose firmware is of that vintage.

       The  COUNT  numeric  argument may include a multiplicative suffix or be
       given in hexadecimal.  See  the  "NUMERIC  ARGUMENTS"  section  in  the
       sg3_utils(8) man page.

       The  SCSI  SANITIZE  command was introduced in SBC-3 revision 27. It is
       closely related to the ATA sanitize disk feature set and can be used to
       remove  all  existing  data  from a disk. Sanitize is more likely to be
       implemented on modern disks (including SSDs) than FORMAT  UNIT's  secu-
       rity  initialization  feature  (see  the --security option) and in some
       cases much faster.

       SSDs that support thin provisioning will typically  unmap  all  logical
       blocks  during  a format. The reason is to improve the SSD's endurance.
       Also thin provisioned formats typically complete faster than fully pro-
       visioned  ones  on  the  same disk (see the --ip_def option). In either
       case format operations on SSDs tend to be a lot faster than they are on
       hard disks with spinning media.

       Tape  system  use  a  variant of the FORMAT UNIT command used on disks.
       Tape systems use the FORMAT MEDIUM command which is simpler  with  only
       three  fields  in  the  cdb typically used. Apart from sharing the same
       opcode the cdbs of FORMAT UNIT and FORMAT MEDIUM are  quite  different.
       FORMAT  MEDIUM's  fields  are  VERIFY,  IMMED and FORMAT (with TRANSFER
       LENGTH always set to 0).  The VERIFY bit field is set with the --verify
       option.  The  IMMED bit is manipulated by the --wait option in the same
       way it is for disks; one difference is that if the --poll=PT option  is
       not given then it defaults to PT of 1 which means the poll is done with
       REQUEST SENSE commands.

       The argument given to the --tape=FM option is used to  set  the  FORMAT
       field.  FM  can  take values from "-1" to "15" where "-1" (the default)
       means don't do a tape format; value "8" to "15" are for vendor specific
       formats.  The  --early option may also be used to set the IMMED bit and
       then exit this utility (rather than poll periodically until it is  fin-
       ished). In this case the tape drive will still be busy doing the format
       for some time but, according to T10, should still respond  in  full  to
       the INQUIRY and REPORT LUNS commands. Other commands (including REQUEST
       SENSE) should yield a "not ready" sense key with  an  additional  sense
       code  of  "Logical  unit  not  ready, format in progress". Additionally
       REQUEST SENSE should contain a progress indication in its sense data.

       When FM is 1 or 2 then the settings in the Medium partition  mode  page
       control  the  partitioning.  That  mode page can be viewed and modified
       with the sdparm utility.

       Prior to invoking this utility the tape may need to  be  positioned  to
       the  beginning of partition 0. In Linux that can typically be done with
       the mt utility (e.g. 'mt -f /dev/st0 rewind').

       These examples use Linux device names. For  suitable  device  names  in
       other supported Operating Systems see the sg3_utils(8) man page.

       In the first example below simply find out the existing block count and
       size derived from two sources: a block descriptor in a MODE SELECT com-
       mand  response  and  from  the response of a READ CAPACITY commands. No
       changes are made:

          # sg_format /dev/sdm

       Now a simple format, leaving the block count and size as they were pre-
       viously.   The  FORMAT  UNIT  command is executed in IMMED mode and the
       device is polled every 60 seconds to print out a progress indication:

          # sg_format --format /dev/sdm

       Now the same format, but waiting (passively) until the format operation
       is complete:

          # sg_format --format --wait /dev/sdm

       Next  is  a  format in which the block size is changed to 520 bytes and
       the block count is set to the manufacturer's maximum  value  (for  that
       block size). Note, not all disks support changing the block size:

          # sg_format --format --size=520 /dev/sdm

       Now a resize operation so that only the first 0x10000 (65536) blocks on
       a disk are accessible. The remaining blocks remain unaltered.

          # sg_format --resize --count=0x10000 /dev/sdm

       Now resize the disk back to its normal (maximum) block count:

          # sg_format --resize --count=-1 /dev/sdm

       One reason to format a SCSI disk  is  to  add  protection  information.
       First check which protection types are supported by a disk (by checking
       the SPT field in the Extended inquiry VPD page together with  the  Pro-
       tect bit in the standard inquiry response):

          # sg_vpd -p ei -l /dev/sdb
          extended INQUIRY data VPD page:
            SPT=1 [protection types 1 and 2 supported]

       Format with type 1 protection:

          # sg_format --format --fmtpinfo=2 /dev/sdm

       After  a  successful  format  with type 1 protection, READ CAPACITY(16)
       should show something like this:

          # sg_readcap -l /dev/sdm
          Read Capacity results:
             Protection: prot_en=1, p_type=0, p_i_exponent=0 [type  1  protec-
             Logical block provisioning: lbpme=0, lbprz=0

       To format with type 3 protection:

          # sg_format --format --fmtpinfo=3 --pfu=1 /dev/sdm

       For  the  disk shown above this will probably fail because the Extended
       inquiry VPD page showed only types 1 and 2 protection are supported.

       The exit status of sg_format is 0 when it is successful. Otherwise  see
       the  sg3_utils(8) man page. Unless the --wait option is given, the exit
       status may not reflect the success of otherwise of the  format.   Using
       sg_turs(8) and sg_readcap(8) after the format operation may be wise.

       Written by Grant Grundler, James Bottomley and Douglas Gilbert.

       Report bugs to <dgilbert at interlog dot com>.

       Copyright  (C)  2005-2016  Grant  Grundler, James Bottomley and Douglas
       This software is distributed under the GPL version 2. There is NO  war-
       ranty;  not  even  for MERCHANTABILITY or FITNESS FOR A PARTICULAR PUR-

       sg_turs(8), sg_requests(8), sg_inq(8), sg_modes(8), sg_vpd(8), sg_reas-
       sign(8),    sg_readcap(8),   sg3_utils(8),   sg_sanitize(8)   [all   in
       sg3_utils], mt(mt-st), sdparm(8), scsiformat (old), hdparm(8)

       This    software    was    built    from    source     available     at
       https://github.com/oracle/solaris-userland.    The  original  community
       source was downloaded from  http://sg.danny.cz/sg/p/sg3_utils-1.42.tgz

       Further information about this software can be found on the open source
       community website at http://sg.danny.cz/sg/sg3_utils.html.

sg3_utils-1.42                   February 2016                    SG_FORMAT(8)