Provided by: sg3-utils_1.44-1ubuntu2_amd64 bug

NAME

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

SYNOPSIS

       sg_format  [--cmplst={0|1}] [--count=COUNT] [--dcrt] [--dry-run] [--early] [--ffmt=FFMT] [--fmtpinfo=FPI]
       [--format]  [--help]  [--ip-def]  [--long]  [--mode=MP]  [--pfu=PFU]  [--pie=PIE]  [--pinfo]  [--poll=PT]
       [--quick]   [--resize]  [--rto_req]  [--security]  [--six]  [--size=LB_SZ]  [--tape=FM]  [--timeout=SECS]
       [--verbose] [--verify] [--version] [--wait] DEVICE

DESCRIPTION

       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 recommends. The manufacturer's recommendation typically leaves
       aside a certain 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 accessible 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. There is a  Format
       Status log page which reports on the previous successful format operation(s).

       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 CAPACITY command.  The  reason  for  this
       double  check  is  to detect a "format corrupt" state (see the NOTES section). This usage will not modify
       the disk.

       When this utility is used with the "--format" (or "-F") option  it  will  attempt  to  format  the  given
       DEVICE.  In  the  absence  of the --quick option 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 (PI) is optional and is made up of one or more protection intervals, each made up
       of 8 bytes associated with a logical block. When PI is active each logical block will have 1,  2,  4,  8,
       etc  protection  intervals (i.e. a power of two), interleaved with (and following) the user data to which
       they refer. 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 the SSC  documents  at  T10  and  prepares  a  volume  for  use.  That  may  include
       partitioning the medium. See the section below on TAPE for more information.

OPTIONS

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

       -C, --cmplst={0|1}
              sets the CMPLST ("complete list") bit in the FORMAT UNIT cdb to 0 or 1.  If the value  is  0  then
              the  existing GLIST (grown list) is taken into account.  If the value is 1 then the existing GLIST
              is ignored. CMPLST defaults to 1 apart from when the --ffmt=FFMT option's  value  is  non-zero  in
              which  case  CMPLST  defaults  to 0. See the LISTS section below. In most cases this bit should be
              left at its default value.

       -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 is:
                (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
                (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 interpretation:
                (COUNT > 0) : after resize READ CAPACITY will report COUNT blocks
                (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". Certification 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.

       -d, --dry-run
              this option will parse the command line, do all the preparation but bypass the actual FORMAT  UNIT
              or  FORMAT MEDIUM commands. Also if the options would cause the logical block size to change, then
              the MODE SELECT command that would do that is also bypassed when the dry run option is given.

       -e, --early
              during a format operation, The default action of this utility is to poll the disk every 60 seconds
              (or every 10 seconds if FFMT is non-zero) 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 (fast format) 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 which is
              typically to overwrite all blocks on the DEVICE. That can take a long time (e.g. with  hard  disks
              over  10 TB in size that can be days). With FFMT set that time may be reduced to minutes. So it is
              worth trying if it is available.
              FFMT has values 1 and 2 for fast format with 3 being reserved currently. These two values  include
              this  description:  "The  device  server initializes the medium ... without overwriting the medium
              (i.e. resources for managing medium access are initialized and the medium is not  written)".   The
              difference  between 1 and 2 concerns read operations on LBAs to which no data has been written to,
              after 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 may yield check condition
              status with a sense key set to hardware error, medium error or command aborted. See SBC-4 revision
              15 section 4.35 for more details.

       -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  revision  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. In the absence of the --quick option, 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 section 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. associate 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. Also accepts --ip_def for this option.

       -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 depending other parameters (e.g. when '--pie=PIE' is greater than zero).

       -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 page.
              Preferably the chosen (or default) mode page should be saveable (i.e.  accept the SP  bit  set  in
              the MODE SELECT command used when the logical block size is being changed). Recent version of this
              utility  will  retry  a MODE SELECT if the SP=1 variant fails with a sense key of ILLEGAL REQUEST.
              That retry will use the same MODE SELECT command but with SP=0 .

       -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
              PROTECTION 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.

       -Q, --quick
              the default action (i.e. when the option is  not  given)  is  to  give  the  user  15  seconds  to
              reconsider  doing a format operation on the DEVICE.  When this option is given that step (i.e. the
              15 second warning period) is skipped.

       -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=LB_SZ 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=LB_SZ
              where LB_SZ is the logical block size (i.e. number of user 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 command. 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
              recommended in the SBC standards). Some SCSI disks have 512 byte logical  blocks  by  default  and
              allow  an  alternate  logical  block  size of 4096 bytes. If the given size in unacceptable to the
              disk, most likely an "Invalid field in parameter list" message will appear in sense data (requires
              the use of '-v' to decode sense data).
              Note that formatting a disk to add or remove protection information is not regarded as a change to
              its logical block size so this option should not be used.

       -T, --tape=FM
              will send a FORMAT MEDIUM command to the DEVICE with its 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.

       -m, --timeout=SECS
              where SECS is the FORMAT UNIT or FORMAT MEDIUM command timeout in seconds. SECS will only be  used
              if  it  exceeds the internal timeout which is 20 seconds if the IMMED bit is set and 72000 seconds
              (20 hours) or higher if the IMMED bit is not set. If the disk size exceeds 4 TB then  the  timeout
              value  is  increased to 144000 seconds (40 hours). And if it is greater than 8 TB then the timeout
              value is increased to 288000 seconds (80 hours). If the timeout is  exceeded  then  the  operating
              system  will  typically  abort  the  command.  Aborting  a command may escalate to a LUN reset (or
              worse). A timeout may also leave the disk or tape format operation incomplete. And that may result
              in the disk or tape being in a "format corrupt" state  requiring  another  format  to  remedy  the
              situation. So for various reasons timeouts are best avoided.

       -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 tapes.

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

       -w, --wait
              the default format action is to set the "IMMED" bit in the FORMAT 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
              then  the  FORMAT  UNIT or FORMAT MEDIUM command waits until the format operation completes before
              returning its response. This can be many hours on large disks. See the --timeout=SECS option.

LISTS

       The SBC-3 draft (revision 20) defines PLIST, CLIST, DLIST and GLIST in section 4.10 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)).

       By the SBC-3 standard (following draft revision 36) the CLIST and DLIST had been removed,  leaving  PLIST
       and GLIST. Only PLIST and GLIST are found in the SBC-4 drafts.

       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

       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
       protection intervals interleaved in each logical block. Each protection interval follows the user data to
       which it refers. A protection interval contains 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 reference 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 considered to be 512 and 4096 bytes respectively.

       The  SBC-3  standard  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-formatted.  For more information see the Protection Information
       in section 4.22 of draft SBC-4 revision 15.

       A device that supports PI information (i.e. supports one or more protection 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 protection types followed by the options of this utility needed to select
       them:
         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
       chosen.

NOTES

       After a format that changes the logical block size or the  number  of  logical  blocks  on  a  disk,  the
       operating  system  may  need  to be told to re-initialize its setting for that disk. In Linux that can be
       done with:
           echo 1 > /sys/block/sd{letter(s)}/device/rescan
       where "letter(s)" will be between 'a' and 'zzz'. The lsscsi utility in Linux can be  used  to  check  the
       various namings of a disk.

       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
       commands 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.  Otherwise the DEVICE is polled every 60
       seconds or every 10 seconds if FFMT is non-zero. The poll is  with  TEST  UNIT  READY  or  REQUEST  SENSE
       commands  until  one  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 (or --tape) 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 leaving those commands queued behind the active format command. This may cause a timeout  in  the
       OS  driver  (in a lot shorter period than 20 hours applicable to some format operations). This may result
       in the OS resetting the disk leaving the format operation incomplete.  This  may  leave  the  disk  in  a
       "format corrupt" state requiring another format to remedy the situation. Modern SCSI devices should yield
       a  "not  ready" sense key with an additional sense indicating a format is in progress. With older devices
       the user should take precautions that nothing attempts to access a device while it is being formatted.

       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 standard calls "format corrupt". A
       block descriptor in a subsequent MODE SENSE will report  the  requested  new  block  size  while  a  READ
       CAPACITY  command  will  report  the existing (i.e. previous) block size. Alternatively the READ CAPACITY
       command may fail, reporting the device is not ready, potentially requiring a format. The solution to this
       situation 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 size.

       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 operation.  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 corresponds to '-1'. So a --count=-1 causes the block count to  be  set
       back  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.

       The FMTDATA field shown in the FORMAT UNIT cdb does not have a corresponding option in this utility. When
       set in the cdb it indicates an additional parameter list will be sent to the DEVICE along with  the  cdb.
       It is set as required, basically when any field in the parameter list header is set.

       Short  stroking  is a technique to trade off capacity for performance on hard disks. "Hard" disk is often
       used to mean a storage device with spinning platters which contain the user data. Solid State Disk  (SSD)
       is  the  newer  form  of  storage  device that contains no moving parts. Hard disk performance is usually
       highest on the outer tracks (usually the 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 information (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 security 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
       provisioned  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

       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 finished). 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').

EXAMPLES

       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 command 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 previously.  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 Protect
       bit in the standard inquiry response):

          # sg_vpd -p ei -l /dev/sdb
          extended INQUIRY data VPD page:
            ACTIVATE_MICROCODE=0
            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 protection]
             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.

       Here are examples of using fast format (FFMT field in FORMAT UNIT cdb) to quickly switch between 512  and
       4096 byte logical block size. Assume disk starts with 4096 byte logical block size and all important data
       has been backed up.

          # sg_format --format --ffmt=1 --size=512 /dev/sdd

       Now /dev/sdd should have 512 byte logical block size. And to switch it back:

          # sg_format --format --ffmt=1 --size=4096 /dev/sdd

EXIT STATUS

       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.

AUTHORS

       Written by Grant Grundler, James Bottomley and Douglas Gilbert.

REPORTING BUGS

       Report bugs to <dgilbert at interlog dot com>.

COPYRIGHT

       Copyright © 2005-2018 Grant Grundler, James Bottomley and Douglas Gilbert
       This  software is distributed under the GPL version 2. There is NO warranty; not even for MERCHANTABILITY
       or FITNESS FOR A PARTICULAR PURPOSE.

SEE ALSO

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

sg3_utils-1.43                                   September 2018                                     SG_FORMAT(8)