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


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


       Sends one or more SCSI VERIFY commands to DEVICE. It  is  the  10  byte
       VERIFY    command   defined   for   block   devices   (see   SBC-2   at  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
       necessary 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).


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

       -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
              commands  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)

       -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
              command  cdb.  It must be a value between 0 and 7 inclusive. The
              default value is zero.


       Various  numeric  arguments  (e.g.  LBA)  may  include   multiplicative
       suffixes  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.


       The  exit status of sg_verify 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 © 2004-2009 Douglas Gilbert
       This software is distributed under  a  FreeBSD  license.  There  is  NO
       warranty;  not  even  for  MERCHANTABILITY  or FITNESS FOR A PARTICULAR


       sginfo(sg3_utils),     sg_modes(sg3_utils),      sg_readcap(sg3_utils),