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SuSE 11.3 - man page for sg_requests (suse section 8)


       sg_requests - send one or more SCSI REQUEST SENSE commands

       sg_requests  [--desc]  [--help]	[--hex]  [--maxlen=LEN]  [--num=NUM] [--progress] [--raw]
       [--status] [--time] [--verbose] [--version] DEVICE

       Send SCSI REQUEST SENSE command to DEVICE and output the parameter data response which  is
       expected to be in sense data format. Both fixed and descriptor sense data formats are sup-

       Multiple REQUEST SENSE commands can be sent with the --num=NUM option. This  can  be  used
       for timing purposes or monitoring the progress indication.

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

       -d, --desc
	      sets  the  DESC  bit  in the REQUEST SENSE SCSI cdb. The DEVICE should return sense
	      data in descriptor (rather than fixed) format. This will only occur if  the  DEVICE
	      recognizes  descriptor  format  (SPC-3  and later). If the device is pre SPC-3 then
	      setting a bit in a reserved field may cause a check condition status with an  ille-
	      gal request sense key, but will most likely be ignored.

       -h, --help
	      output the usage message then exit.

       -H, --hex
	      output response in ASCII hexadecimal.

       -m, --maxlen=LEN
	      where  LEN  is  the  (maximum)  response length in bytes. It is placed in the cdb's
	      "allocation length" field. If not given (or LEN is zero) then 252 is used. The max-
	      imum value of LEN is 255 (but SPC-4 recommends 252).

       -n, --num=NUM
	      perform  NUM SCSI REQUEST SENSE commands, stopping when either NUM is reached or an
	      error occurs. The default value for NUM is 1 .

       -p, --progress
	      show progress indication (a percentage) if available. If --number=NUM is given, NUM
	      is greater than 1 and an initial progress indication was detected then this utility
	      waits 30 seconds before subsequent checks.  Exits when NUM is reached or there  are
	      no  more	progress indications.  Ignores --hex, --raw and --time options. See NOTES
	      section below.

       -r, --raw
	      output response in binary (to stdout).

       -s, --status
	      if the REQUEST SENSE command finished without error (as indicated by its SCSI  sta-
	      tus)  then  the  contents  of the parameter data are analysed as sense data and the
	      exit status is set accordingly. The default action (i.e. when this  option  is  not
	      given)  is to ignore the contents of the parameter data for the purposes of setting
	      the exit status.	Some types of error set a sense key of "NO SENSE"  with  non-zero
	      information  in  the  additional	sense code (e.g. the FAILURE PREDICTION THRESHOLD
	      EXCEEDED group of codes); this results in an exit status value of 10. If the  sense
	      key is "NO SENSE" and both asc and ascq are zero then the exit status is set to 0 .
	      See the sg3_utils(8) man page for exit status values.

       -t, --time
	      time the SCSI REQUEST SENSE command(s) and calculate the average number  of  opera-
	      tions per second.

       -v, --verbose
	      increase	the  level  of verbosity, (i.e. debug output).	Additionally the response
	      (if received) is output in ASCII-HEX. Use this option multiple  times  for  greater

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

       In  SCSI  1  and 2 the REQUEST SENSE command was very important for error and warning pro-
       cessing in SCSI. The autosense capability rendered this command almost superfluous.

       However recent SCSI drafts (e.g. SPC-4 rev 14 and SBC-3 rev 14) increase  the  utility  of
       the  REQUEST  SENSE  command. Idle and standby (low) power conditions can be detected with
       this command.

       The REQUEST SENSE command is not marked as mandatory in SPC-3 (i.e. for all SCSI  devices)
       but  is	marked	as  mandatory in SBC-2 (i.e. for disks), SSC-3 (i.e. for tapes) and MMC-4
       (i.e. for CD/DVD/HD-DVD/BD drives).

       The progress indication is optionally part of the sense data. When a  prior  command  that
       takes  a  long  time  to complete (and typically precludes other media access commands) is
       still underway, the progress indication can be used  to	determine  how	long  before  the
       device returns to its normal state.

       The  SCSI  FORMAT command for disks used with the IMMED bit set is an example of an opera-
       tion that takes a significant amount of time and precludes other media access during  that
       time.  The IMMED bit set instructs the FORMAT command to return control to the application
       client once the format has commenced (see SBC-3).  Several  long  duration  SCSI  commands
       associated with tape drives also use the progress indication (see SSC-3).

       Early  standards  suggested  that the SCSI TEST UNIT READY command be used for polling the
       progress indication. More recent standards seem to suggest the SCSI REQUEST SENSE  command
       should be used instead.

       The  exit status of sg_requests is 0 when it is successful. Otherwise see the sg3_utils(8)
       man page.

       Written by Douglas Gilbert.

       Report bugs to <dgilbert at interlog dot com>.

       Copyright (C) 2004-2008 Douglas Gilbert
       This software is distributed under a FreeBSD license. There is NO warranty; not	even  for


sg3_utils-1.26				    April 2008				   SG_REQUESTS(8)

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