Provided by: sg3-utils_1.17-2_i386 bug

NAME

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

SYNOPSIS

       sg_verify   [--bpc=<n>]   [--count=<n>]  [--dpo]  [--help]  [--lba=<n>]
       [--verbose] [--version] <scsi_device>

DESCRIPTION

       Sends one or more SCSI VERIFY commands to the given Linux SCSI  device.
       It  is a 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=<n>’  option and continues for ’--count=<n>’ blocks. No
       more than ’--bpc=<n>’ 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).

       --bpc=<n> | -b <n>
              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 the
              value <n> is less than the value given to --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.

       --dpo | -d
              disable  page  out  changes the cache retention policy 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.

       --count=<n> | -c <n>
              specifies the number of blocks to verify. The default value is 1
              .   If <n> is greater than the value associated with ’--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.

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

       --lba=<n> | -l <n>
              specifies  the  logical block address on the device to start the
              verify operation. <n> is assumed to be decimal  unless  prefixed
              by  ’0x’  (see below). The default value is 0 (i.e. the start of
              the device).

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

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

       The arguments to --bpc, --count and --lba may be  followed  by  one  of
       these  multiplicative  suffixes:  c  C  *1;  w  W *2; b B *512; k K KiB
       *1,024; KB  *1,000;  m  M  MiB  *1,048,576;  MB  *1,000,000;  g  G  GiB
       *1,073,741,824;  GB *1,000,000,000; t T TiB *(2**40); TB *(10**12); p P
       PiB *(2**50) and PB *(10**15). The "T" and "P" based suffixes can  only
       be  used  for  --count  and  --lba.  Also  a  suffix of the form "x<n>"
       multiplies the leading number by <n>.

       Alternatively numerical values can be given in hexadecimal preceded  by
       either  "0x"  or "0X". When hex numbers are given multipliers cannot be
       used.

       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.

AUTHORS

       Written by Douglas Gilbert.

REPORTING BUGS

       Report bugs to <dgilbert at interlog dot com>.

COPYRIGHT

       Copyright © 2004-2005 Douglas Gilbert
       This  software  is  distributed  under  a  FreeBSD license. There is NO
       warranty; not even for MERCHANTABILITY  or  FITNESS  FOR  A  PARTICULAR
       PURPOSE.

SEE ALSO

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