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 SOFTWARE, EVEN IF ADVISED OF THE
       POSSIBILITY OF SUCH DAMAGE.

SEE ALSO

       sg_xcopy, sg_receive_copy_results(sg3_utils)

sg3_utils-1.36                                      May 2013                                COMPARE AND WRITE(8)