NAME

       sg_compare_and_write - send the SCSI COMPARE AND WRITE command

SYNOPSIS

       sg_compare_and_write  [--dpo]  [--fua]  [--fua_nv]  [--help] --in=IF --lba=LBA [--num=NUM]
       [--timeout=TO] [--verbose] [--version] [--wrprotect=WP] [--xferlen=LEN] DEVICE

DESCRIPTION

       Send the SCSI COMPARE AND WRITE command to DEVICE. This command  receives  a  data  buffer
       which  contains  a  verify  instance  and a write instance each containing num blocks, the
       DEVICE will read num blocks starting at logical block address LBA, compare the  data  read
       from  the  specified  blocks  to  the  verify  instance and if they match, write the write
       instance to the DEVICE at the same logical block address LBA.  All of the above operations
       shall be performed as an uninterrupted series of actions.

       The  data buffer which contains the verify and write instances are obtained from the input
       file IF, this file is expected to be 2*num blocks long. If bs is not specified, then  READ
       CAPACITY(10) is used to determine the block size. If not specified, the transfer size will
       be the 2*num blocks.

       In case of a mismatch between the blocks read from DEVICE and the verify instance  in  the
       data buffer, a check condition will be returned with sense key set to miscompare.

       This  command  is defined in SBC-3 whose most recent revision is 35d. SBC-3 and other SCSI
       documents can be found at http://www.t10.org .

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.

       -d, --dpo
              Set the DPO bit in the COMPARE AND WRITE CDB

       -f, --fua
              Set the FUA bit in the COMPARE AND WRITE CDB

       -F, --fua_nv
              Set  the  FUA_NV  bit  in  the COMPARE AND WRITE CDB. This bit was removed in SBC-3
              revision 35d and its position marked as "reserved".

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

       -i, --in=IF
              read data (binary) from file named IF and use it as the data  out  buffer  for  the
              SCSI COMPARE AND WRITE command. The IF shall be at 2*NUM blocks.

       -l, --lba=LBA
              where  LBA  is  the  logical  block address to start the COMPARE AND WRITE command.
              Assumed to be in decimal unless prefixed with '0x' or has a trailing 'h'.

       -n, --num=NUM
              where NUM is the number of blocks, starting at LBA, to read and  compare  with  the
              verify  instance.  And  given a match, the NUM of blocks to write starting LBA. The
              default value for NUM is 1.

       -t, --timeout=TO
              where TO is the command timeout value in seconds. The default value is 60  seconds.
              If  NUM  is large (or zero) a WRITE SAME command may require considerably more time
              than 60 seconds to complete.

       -v, --verbose
              increase the degree of verbosity (debug messages).

       -V, --version
              output version string then exit.

       -w, --wrprotect=WP
              set the WRPROTECT field in the cdb to WP. The default value is 0 which  implies  no
              protection information is sent (along with the user data) by this utility.

       -x, --xferlen=LEN
              where LEN is the data out buffer length. Defaults to 2*NUM blocks.

NOTES

       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.

EXIT STATUS

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

AUTHORS

       Written by Shahar Salzman.

REPORTING BUGS

       Report bugs to shahar.salzman@kaminario.com

COPYRIGHT

       Copyright © 2012-2013 Kaminario Technologies LTD

       Redistribution  and  use  in  source  and  binary forms, with or without modification, are
       permitted provided that the following conditions are met:
       * Redistributions of source code must retain the above  copyright  notice,  this  list  of
       conditions and the following disclaimer.
       *  Redistributions  in binary form must reproduce the above copyright notice, this list of
       conditions and the following  disclaimer  in  the  documentation  and/or  other  materials
       provided with the distribution.
       *  Neither the name of the <organization> nor the names of its contributors may be used to
       endorse or promote products derived from this  software  without  specific  prior  written
       permission.

       THIS  SOFTWARE  IS  PROVIDED  BY  THE  COPYRIGHT  HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
       EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE  IMPLIED  WARRANTIES  OF
       MERCHANTABILITY  AND  FITNESS  FOR  A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
       Kaminario Technologies LTD BE  LIABLE  FOR  ANY  DIRECT,  INDIRECT,  INCIDENTAL,  SPECIAL,
       EXEMPLARY,  OR  CONSEQUENTIAL  DAMAGES  (INCLUDING,  BUT  NOT  LIMITED  TO, PROCUREMENT OF
       SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR  PROFITS;  OR  BUSINESS  INTERRUPTION)
       HOWEVER  CAUSED  AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
       TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN  ANY  WAY  OUT  OF  THE  USE  OF  THIS
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SEE ALSO

       sg_xcopy, sg_receive_copy_results(sg3_utils)