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SG_WRITE_BUFFER(8)		   SG3_UTILS		    SG_WRITE_BUFFER(8)

NAME
       sg_write_buffer - send SCSI WRITE BUFFER	commands

SYNOPSIS
       sg_write_buffer	   [--bpw=CS]	  [--help]    [--id=ID]	   [--in=FILE]
       [--length=LEN] [--mode=MO] [--offset=OFF] [--raw] [--skip=SKIP] [--spe-
       cific=MS] [--timeout=TO]	[--verbose] [--version]	DEVICE

DESCRIPTION
       Sends one or more SCSI WRITE BUFFER commands to DEVICE, along with data
       provided	by the user. In	some cases no data is required,	or data	can be
       read  from the file given in the	--in=FILE option, or data is read from
       stdin when either --raw or --in=- is given.

       Some WRITE BUFFER command variants do not have associated data to  send
       to  the	device.	For example "activate_mc" activates deferred microcode
       that was	sent via prior WRITE BUFFER commands.  There  is  a  different
       method  used  to	 download microcode to SES devices, see	the sg_ses_mi-
       crocode utility.

OPTIONS
       Arguments to long options are mandatory for short options as well.

       -b, --bpw=CS
	      where CS is the chunk size in bytes. This	will  be  the  maximum
	      number  of bytes sent per	WRITE BUFFER command. So if CS is less
	      than the effective length	then multiple  WRITE  BUFFER  commands
	      are  sent, each taking the next chunk from the read data and in-
	      creasing the buffer offset field in the WRITE BUFFER command  by
	      the  appropriate	amount.	The default is a chunk size of 0 which
	      is interpreted as	a very large number hence only one WRITE  BUF-
	      FER  command  will be sent. This option should only be used with
	      modes that "download microcode, with offsets ..."; namely	either
	      mode 0x6,	0x7, 0xd or 0xe.
	      The number in CS can optionally be followed by ",act" or ",acti-
	      vate".  In this case after WRITE BUFFER commands have been  sent
	      until  the  effective  length  is	exhausted another WRITE	BUFFER
	      command with its mode set	to "Activate deferred microcode	 mode"
	      [mode 0xf] is sent.

       -h, --help
	      output  the usage	message	then exit. If used multiple times also
	      prints the mode names and	their acronyms.

       -i, --id=ID
	      this option sets the buffer id field in the cdb. ID is  a	 value
	      between 0	(default) and 255 inclusive.

       -I, --in=FILE
	      read data	from file FILE that will be sent with the WRITE	BUFFER
	      command.	If FILE	is '-' then stdin is read until	an EOF is  de-
	      tected (this is the same action as --raw). Data is read from the
	      beginning	of FILE	except in the case when	it is a	 regular  file
	      and the --skip=SKIP option is given.

       -l, --length=LEN
	      where  LEN is the	length,	in bytes, of data to be	written	to the
	      device.  If not given (and the length  cannot  be	 deduced  from
	      --in=FILE	 or  --raw)  then  defaults  to	zero. If the option is
	      given and	the length deduced from	--in=FILE or --raw is less (or
	      no data is provided), then bytes of 0xff are used	as fill	bytes.

       -m, --mode=MO
	      this  option  sets  the MODE field in the	cdb. MO	is a value be-
	      tween 0 (default)	and 31 inclusive. Alternatively	 an  abbrevia-
	      tion  can	 be  given.   See the MODES section below. To list the
	      available	mode abbreviations at run time	give  an  invalid  one
	      (e.g. '--mode=xxx') or use the '-hh' option.

       -o, --offset=OFF
	      this  option  sets  the BUFFER OFFSET field in the cdb. OFF is a
	      value between 0 (default)	and 2**24-1 . It is a byte offset.

       -r, --raw
	      read data	from stdin until an EOF	is detected. This data is sent
	      with  the	WRITE BUFFER command to	DEVICE.	The action of this op-
	      tion is the same as using	'--in=-'.

       -s, --skip=SKIP
	      this option is only active when --in=FILE	is given and FILE is a
	      regular  file,  rather than stdin. Data is read starting at byte
	      offset SKIP  to  the  end	 of  file  (or	the  amount  given  by
	      --length=LEN).  If not given the byte offset defaults to 0 (i.e.
	      the start	of the file).

       -S, --specific=MS
	      MS is the	MODE SPECIFIC field in the cdb.	This is	a 3-bit	 field
	      so  the values 0 to 7 are	accepted. This field was introduced in
	      SPC-4 revision 32	and can	be used	to specify  additional	events
	      that activate deferred microcode (when MO	is 0xD).

       -t, --timeout=TO
	      TO  is  the  command  timeout (in	seconds) for each WRITE	BUFFER
	      command issued by	this utility. Its default value	is 300 seconds
	      (5  minutes)  and	 should	 only be altered if this is not	suffi-
	      cient.

       -v, --verbose
	      increase the level of verbosity, (i.e. debug output).

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

MODES
       Following is a list of WRITE  BUFFER  command  settings	for  the  MODE
       field.	First  is an acronym accepted by the MO	argument of this util-
       ity.  Following the acronym in square brackets  are  the	 corresponding
       decimal and hex values that may also be given for MO. The following are
       listed in numerical order.

       hd  [0, 0x0]
	      Combined header and data (obsolete in SPC-4).

       vendor  [1, 0x1]
	      Vendor specific.

       data  [2, 0x2]
	      Data (was	called "Write Data" in SPC-3).

       dmc  [4,	0x4]
	      Download microcode and activate (was called "Download microcode"
	      in SPC-3).

       dmc_save	 [5, 0x5]
	      Download microcode, save,	and activate (was called "Download mi-
	      crocode and save"	in SPC-3).

       dmc_offs	 [6, 0x6]
	      Download microcode with offsets and activate (was	called	"Down-
	      load microcode with offsets" in SPC-3).

       dmc_offs_save  [7, 0x7]
	      Download	microcode with offsets,	save, and activate (was	called
	      "Download	microcode with offsets and save" in SPC-3).

       echo  [10, 0xa]
	      Write data to echo buffer	(was called "Echo buffer" in SPC-3).

       dmc_offs_ev_defer  [13, 0xd]
	      Download microcode with offsets, select activation events, save,
	      and defer	activate (introduced in	SPC-4).

       dmc_offs_defer  [14, 0xe]
	      Download	microcode  with	offsets, save, and defer activate (in-
	      troduced in SPC-4).

       activate_mc  [15, 0xf]
	      Activate deferred	microcode (introduced in SPC-4).

       en_ex  [26, 0x1A]
	      Enable expander communications protocol and Echo	buffer	(obso-
	      lete in SPC-4).

       dis_ex  [27, 0x1B]
	      Disable expander communications protocol (obsolete in SPC-4).

       deh  [28, 0x1C]
	      Download	application client error history (was called "Download
	      application log" in SPC-3).

NOTES
       If no --length=LEN is given this	utility	reads up to 8 MiB of data from
       the  given file FILE (or	stdin).	If a larger amount of data is required
       then the	--length=LEN option should be given.

       The user	should be aware	that most operating systems have limits	on the
       amount  of  data	 that can be sent with one SCSI	command. In Linux this
       depends on the pass through mechanism used (e.g.	block SG_IO or the  sg
       driver) and various setting in sysfs in the Linux lk 2.6/3 series (e.g.
       /sys/block/sda/queue/max_sectors_kb). Devices (i.e. logical units) also
       typically  have limits on the maximum amount of data they can handle in
       one command. These two limitations suggest that	modes  containing  the
       word  "offset"  together	 with  the  --bpw=CS  option  are  required as
       firmware	files get larger and larger. And CS can	be  quite  small,  for
       example 4096 bytes, resulting in	many WRITE BUFFER commands being sent.

       Attempting  to download a microcode/firmware file that is too large may
       cause an	error to occur in the pass-through layer (i.e. before the SCSI
       command	is  issued).  In Linux such error reports can be obscure as in
       "pass through os	error invalid argument". FreeBSD reports  such	errors
       well  to	 the  machine's	console	but returns a cryptic error message to
       this utility.

       Downloading incorrect microcode into a device has the ability to	render
       that  device inoperable.	One would hope that the	device vendor verifies
       the data	before activating it. If the  SCSI  WRITE  BUFFER  command  is
       given  values  in  its  cdb (e.g. LEN) that are inappropriate (e.g. too
       large) then the device should respond with a sense key of  ILLEGAL  RE-
       QUEST  and an additional	sense code of INVALID FIELD in CDB. If a WRITE
       BUFFER command (or a sequence of	them) fails due	to device vendor veri-
       fication	 checks	then it	should respond with a sense key	of ILLEGAL RE-
       QUEST and an additional sense code of COMMAND SEQUENCE ERROR.

       All numbers given with options are assumed  to  be  decimal.   Alterna-
       tively  numerical values	can be given in	hexadecimal preceded by	either
       "0x" or "0X" (or	has a trailing "h" or "H").

EXAMPLES
       The following sends new firmware	to an enclosure. Sending a 1.5 MB file
       in one WRITE BUFFER command caused the enclosure	to lock	up temporarily
       and did not update the firmware.	Breaking the firmware file into	 4  KB
       chunks (an educated guess) was more successful:

	 sg_write_buffer -b 4k -m dmc_offs_save	-I firmware.bin	/dev/sg4

       The  firmware  update  occurred in the following	enclosure power	cycle.
       With a modern enclosure the Extended Inquiry VPD	page gives indications
       in which	situations a firmware upgrade will take	place.

EXIT STATUS
       The  exit  status of sg_write_buffer is 0 when it is successful.	Other-
       wise see	the sg3_utils(8) man page.

AUTHORS
       Written by Luben	Tuikov and Douglas Gilbert.

REPORTING BUGS
       Report bugs to <dgilbert	at interlog dot	com>.

COPYRIGHT
       Copyright (C) 2006-2015 Luben Tuikov and	Douglas	Gilbert
       This software is	distributed under a FreeBSD license. There is NO  war-
       ranty;  not  even  for MERCHANTABILITY or FITNESS FOR A PARTICULAR PUR-
       POSE.

SEE ALSO
       sg_read_buffer, sg_ses_microcode(sg3_utils)

sg3_utils-1.41			 February 2015		    SG_WRITE_BUFFER(8)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | MODES | NOTES | EXAMPLES | EXIT STATUS | AUTHORS | REPORTING BUGS | COPYRIGHT | SEE ALSO

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