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SG_VERIFY(8)			   SG3_UTILS			  SG_VERIFY(8)

NAME
       sg_verify - invoke SCSI VERIFY command(s) on a block device

SYNOPSIS
       sg_verify  [--bpc=BPC]  [--count=COUNT]	[--dpo]	 [--help]  [--lba=LBA]
       [--verbose] [--version] [--vrprotect=VRP] DEVICE

DESCRIPTION
       Sends one or more SCSI VERIFY commands to DEVICE. It  is	 the  10  byte
       VERIFY	 command   defined   for   block   devices   (see   SBC-2   at
       http://www.t10.org).  Verify starts at the logical block address	 given
       by the --lba=LBA option and continues for --count=COUNT blocks. No more
       than --bpc=BPC blocks are verified by each VERIFY command so if	neces‐
       sary  multiple  VERIFY commands are sent. No news is good news (i.e. if
       there are no verify errors detected no messages are sent to stderr  and
       the Unix return status is 0).

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.

       -b, --bpc=BPC
	      where  BPC  specifies  the maximum number of blocks that will be
	      verified by a single SCSI VERIFY command. The default  value  is
	      128  blocks  which  equates  to  64  KB for a disk with 512 byte
	      blocks. If BPC is less than COUNT then multiple SCSI VERIFY com‐
	      mands  are  sent to the device. For recent block devices (disks)
	      this value may be constrained by	the  maximum  transfer	length
	      field in the block limits VPD page.

       -c, --count=COUNT
	      where  COUNT  specifies  the  number  of	blocks	to verify. The
	      default value is 1 . If  COUNT  is  greater  than	 BPC  (or  its
	      default  value  of  128)	then multiple SCSI VERIFY commands are
	      sent to the device. The sg_readcap utility can be used  to  find
	      the  maximum  number of blocks that a block device (e.g. a disk)
	      has.

       -d, --dpo
	      disable page out changes the cache retention priority of	blocks
	      read  on	the  device's cache to the lowest priority. This means
	      that blocks read by other commands are more likely to remain  in
	      the device's cache.

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

       -l, --lba=LBA
	      where LBA specifies the logical block address of the first block
	      to start the verify operation. LBA  is  assumed  to  be  decimal
	      unless  prefixed	by  '0x'  or  a	 trailing 'h' (see below). The
	      default value is 0 (i.e. the start of the device).

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

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

       -P, --vrprotect=VRP
	      where VRP is the value in the vrprotect field in the VERIFY com‐
	      mand  cdb.  It  must  be	a value between 0 and 7 inclusive. The
	      default value is zero.

NOTES
       Various numeric arguments (e.g. LBA) may	 include  multiplicative  suf‐
       fixes  or  be given in hexadecimal. See the "NUMERIC ARGUMENTS" section
       in the sg3_utils(8) man page.

       The amount of error correction and  the	number	of  retries  attempted
       before  a  block	 is considered defective are controlled in part by the
       Verify Error Recovery mode page.	 A note in the SBC-2 (draft)  standard
       advises	that to minimize the number of checks (and hence have the most
       "sensitive" verify check) do the following in that mode page.  Set  the
       EER bit to 0, the PER bit to 1, the DTE bit to 1, the DCR bit to 1, the
       verify retry count to 0 and the verify error  recovery  timeout	to  0.
       Mode pages can be modified with the sginfo utility.

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

AUTHORS
       Written by Douglas Gilbert.

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

COPYRIGHT
       Copyright © 2004-2009 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
       sginfo(sg3_utils),     sg_modes(sg3_utils),	sg_readcap(sg3_utils),
       sg_inq(sg3_utils)

sg3_utils-1.27			  March 2009			  SG_VERIFY(8)

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