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SG_FORMAT(8)			   SG3_UTILS			  SG_FORMAT(8)

NAME
       sg_format - format, format with preset, resize SCSI disk; format	tape

SYNOPSIS
       sg_format   [--cmplst={0|1}]   [--count=COUNT]	[--dcrt]   [--dry-run]
       [--early] [--ffmt=FFMT] [--fmtmaxlba-fmtpinfo=FPI] [--format]  [--help]
       [--ip-def]   [--long]  [--mode=MP]  [--pfu=PFU]	[--pie=PIE]  [--pinfo]
       [--poll=PT] [--preset=ID] [--quick] [--resize] [--rto_req] [--security]
       [--six] [--size=LB_SZ] [--tape=FM] [--timeout=SECS] [--verbose] [--ver-
       ify] [--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  op-
       eration.	 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  issues  one  of three SCSI format	commands: FORMAT UNIT,
       FORMAT MEDIUM or	FORMAT WITH PRESET. In the following description,  un-
       qualified  sections  will  usually be referring to the SCSI FORMAT UNIT
       command.	Both FORMAT UNIT and FORMAT WITH PRESET	 apply	to  disks  (or
       disk-like devices).  The	FORMAT MEDIUM command is for tapes.

       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. There is a	Format
       Status log page which reports on	the previous successful	format	opera-
       tion(s).

       When  this utility is used without options (i.e.	it is only given a DE-
       VICE 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
       disk.

       When  this  utility  is	used  with  either  --format,  --preset=ID  or
       --tape=FM, 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  oc-
       curs  just  prior  the  SCSI  FORMAT UNIT, FORMAT WITH PRESET or	FORMAT
       MEDIUM command being issued. See	the NOTES section  for	more  informa-
       tion.

       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  fol-
       lowing)	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.

       The FORMAT WITH PRESET was added	in draft SBC-4 revision	18.  A	preset
       pattern,	selected by the	PRESET IDENTIFIER field	(--id=FWPID), is writ-
       ten to the disk.	See the	FORMAT PRESETS VPD page	(0xb8) for a  list  of
       available Format	preset identifiers and their associated	data.

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 de-
	      faults 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  CA-
	      PACITY 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 in-
	      terpretation:
		(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 max-
	      imum 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  pa-
	      rameter list header. It will "disable certification". Certifica-
	      tion verifies that blocks	are usable during the format  process.
	      Using  this  option  may	speed  the  format but --ffmt=FFMT, if
	      available, would probably	be better. The default action of  this
	      utility  (i.e.  when  this  option is not	given) is to clear the
	      DCRT bit thereby requesting "media certification"	 (also	unless
	      another  option needs it,	the FOV	bit will be cleared). When the
	      DCRT bit is set, the FOV bit must	also be	 set  hence  sg_format
	      does that.
	      If  this	option is given	twice then certification is enabled by
	      clearing the DCRT	bit and	setting	the FOV	bit. Both  these  bits
	      are  found in the	parameter list associated with the FORMAT UNIT
	      cdb.

       -d, --dry-run
	      this option will parse the command line, do all the  preparation
	      but  bypass the actual FORMAT UNIT, FORMAT WITH PRESET or	FORMAT
	      MEDIUM command. Also if the options would	 otherwise  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_re-
	      quests(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  or
	      less. 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  de-
	      vice  server  initializes	the medium ... without overwriting the
	      medium (i.e. resources for managing medium access	 are  initial-
	      ized  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 oper-
	      ation should return "unspecified logical block  data"  and  com-
	      plete 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 draft SBC-4 revision 16
	      section 4.34 for more details.

       -b, --fmtmaxlba
	      This option is only active if it	is  given  together  with  the
	      --preset=ID  option.  If	so  it sets the	FMTMAXLBA field	in the
	      FORMAT WITH PRESET command.

       -f, --fmtpinfo=FPI
	      sets the FMTPINFO	field in the FORMAT UNIT cdb to	 a  value  be-
	      tween  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 one	of the three SCSI "format" commands. In	the absence of
	      the --preset=ID and --tape=FM options, the SCSI FORMAT UNIT com-
	      mand is issued.  These commands 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 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. 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 in-
	      ternally.	This option does not set the LONGLIST bit in the  FOR-
	      MAT  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  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  in-
	      stead.  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.

       -E, --preset=ID
	      this  option  instructs this utility to issue a SCSI FORMAT WITH
	      PRESET command. The PRESET IDENTIFIER field in that cdb  is  set
	      to ID. The IMMED field in	that cdb is also set unless the	--wait
	      option is	also given, in which case it is	cleared.

       -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 differ-
	      ent 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 informa-
	      tion 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  de-
	      fault format then	partition.

       -m, --timeout=SECS
	      where  SECS  is  the  FORMAT  UNIT, FORMAT WITH PRESET 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  operat-
	      ing  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 re-
	      sult in the disk or tape being in	a "format corrupt"  state  re-
	      quiring  another format to remedy	the situation.	So for various
	      reasons command 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 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 then the FORMAT UNIT, FORMAT WITH	PRESET or FOR-
	      MAT  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.
	      Alternatively  this option may be	useful when used together with
	      --ffmt=FFMT (and FFMT greater than 0) since the fast format  may
	      only be a	matter of seconds.

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  pro-
       tection	intervals  interleaved	in each	logical	block. Each protection
       interval	follows	the user data to which it refers. A protection	inter-
       val 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 pro-
       tection 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  in-
       troduced	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 de-
       vice 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 4.21 of draft SBC-4 revision 16.

       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 IN-
       QUIRY 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-ob-
       vious 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
       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  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, --preset=ID or --tape=FM option is given without the
       --wait  option  then  the corresponding SCSI 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 re-
       port then sg_format process can be  terminated  (e.g.  with  control-C)
       without	affecting the format operation which continues.	However	a tar-
       get or device reset (or a power cycle) will probably cause  the	format
       to cease	and the	DEVICE to become "format corrupt".

       When  the  --format (--preset=ID	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 for-
       mat  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	opera-
       tion 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  indicat-
       ing  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.  Unmounting  in  mounted  file  systems on a DEVICE prior to
       calling this utility is strongly	advised.

       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	CAPAC-
       ITY command will	report the existing (i.e. previous) block size.	Alter-
       natively	 the  READ  CAPACITY command may fail, reporting the device is
       not ready, potentially requiring	a format. The solution to this	situa-
       tion 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	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 SE-
       LECT command. In	signed (two's complement) arithmetic that value	corre-
       sponds  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	corre-
       sponding	 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 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 ac-
       cess 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 im-
       plemented  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 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
       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 op-
       code  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  RE-
       QUEST 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 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 de-
       vice 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:
	    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 protec-
       tion]
	     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

       Since  fast  formats  can be very quick (a matter of seconds) using the
       --wait option may be appropriate.

       And tu use Format with preset this invocation might be used:

	  # sg_format --preset=1 --fmtmaxlba /dev/sdd

       The FORMAT PRESETS VPD page (0xb8) should be consulted  to  check  that
       Preset  identifier  0x1 is there	and has	the expected format (i.e. "de-
       fault host aware	zoned block device model with 512 bytes	of  user  data
       in each logical block").

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 (C) 2005-2020 Grant Grundler,	James  Bottomley  and  Douglas
       Gilbert
       This  software is distributed under the GPL version 2. There is NO war-
       ranty; not even for MERCHANTABILITY or FITNESS FOR  A  PARTICULAR  PUR-
       POSE.

SEE ALSO
       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],  lsscsi(8),	mt(mt-st),  sdparm(8),	scsiformat  (old), hd-
       parm(8)

sg3_utils-1.45			 January 2020			  SG_FORMAT(8)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | LISTS | PROTECTION INFORMATION | NOTES | TAPE | EXAMPLES | EXIT STATUS | AUTHORS | REPORTING BUGS | COPYRIGHT | SEE ALSO

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