sg_compare_and_write.8

.TH "COMPARE AND WRITE" "8" "January 2013" "sg3_utils\-1.35" SG3_UTILS
.SH NAME
sg_compare_and_write \- send the SCSI COMPARE AND WRITE command
.SH SYNOPSIS
.B sg_compare_and_write
[\fI\-\-dpo\fR] [\fI\-\-fua\fR] [\fI\-\-fua_nv\fR] [\fI\-\-help\fR]
\fI\-\-in=IF\fR \fI\-\-lba=LBA\fR [\fI\-\-num=NUM\fR] [\fI\-\-timeout=TO\fR]
[\fI\-\-verbose\fR] [\fI\-\-version\fR] [\fI\-\-wrprotect=WP\fR]
[\fI\-\-xferlen=LEN\fR] \fIDEVICE\fR
.SH DESCRIPTION
.\" Add any additional description here
Send the SCSI COMPARE AND WRITE command to \fIDEVICE\fR. This command receives
a data buffer which contains a verify instance and a write instance each
containing \fInum\fR blocks, the \fIDEVICE\fR will read \fInum\fR blocks
starting at logical block address \fILBA\fR, compare the data read from
the specified blocks to the verify instance and if they match, write the write
instance to the \fIDEVICE\fR at the same logical block address \fILBA\fR.
All of the above operations shall be performed as an uninteruppted series of
actions.
.PP
The data buffer which contains the verify and write instances are obtained
from the input file \fIIF\fR, this file is expected to be 2*\fInum\fR blocks
long. If \fIbs\fR is not specified, then READ CAPACITY(10) is used to
determine the block size. If not specified, the transfer size will be the
2*\fInum\fR blocks.
.PP
In case of a mismatch between the blocks read from \fIDEVICE\fR and the verify
instance in the data buffer, a check condition will be returned with sense key
set to miscompare.
.SH 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.
.TP
\fB\-d\fR, \fB\-\-dpo\fR
Set the DPO bit in the COMPARE AND WRITE CDB
.TP
\fB\-f\fR, \fB\-\-fua\fR
Set the FUA bit in the COMPARE AND WRITE CDB
.TP
\fB\-F\fR, \fB\-\-fua_nv\fR
Set the FUA_NV bit in the COMPARE AND WRITE CDB
.TP
\fB\-h\fR, \fB\-\-help\fR
output the usage message then exit.
.TP
\fB\-i\fR, \fB\-\-in\fR=\fIIF\fR
read data (binary) from file named \fIIF\fR and use it as the data out
buffer for the SCSI COMPARE AND WRITE command. The \fIIF\fR shall be at
2*\fINUM\fR blocks.
.TP
\fB\-l\fR, \fB\-\-lba\fR=\fILBA\fR
where \fILBA\fR 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'.
.TP
\fB\-n\fR, \fB\-\-num\fR=\fINUM\fR
where \fINUM\fR is the number of blocks, starting at \fILBA\fR, to read
and compare with the verify instance. And given a match, the \fINUM\fR of
blocks to write starting \fILBA\fR. The default value for \fINUM\fR is 1.
.TP
\fB\-t\fR, \fB\-\-timeout\fR=\fITO\fR
where \fITO\fR is the command timeout value in seconds. The default value is
60 seconds. If \fINUM\fR is large (or zero) a WRITE SAME command may require
considerably more time than 60 seconds to complete.
.TP
\fB\-v\fR, \fB\-\-verbose\fR
increase the degree of verbosity (debug messages).
.TP
\fB\-V\fR, \fB\-\-version\fR
output version string then exit.
.TP
\fB\-w\fR, \fB\-\-wrprotect\fR=\fIWP\fR
set the WRPROTECT field in the cdb to \fIWP\fR. The default value is 0 which
implies no protection information is sent (along with the user data) by this
utility.
.TP
\fB\-x\fR, \fB\-\-xferlen\fR=\fILEN\fR
where \fILEN\fR is the data out buffer length. Defaults to 2*\fINUM\fR blocks.
.SH NOTES
Various numeric arguments (e.g. \fILBA\fR) may include multiplicative
suffixes or be given in hexadecimal. See the "NUMERIC ARGUMENTS" section
in the sg3_utils(8) man page.
.SH EXIT STATUS
The exit status of sg_compare_and_write is 0 when it is successful. Otherwise
see the sg3_utils(8) man page.
.SH AUTHORS
Written by Shahar Salzman.
.SH "REPORTING BUGS"
Report bugs to shahar.salzman@kaminario.com
.SH COPYRIGHT
Copyright \(co 2012\-2013 Kaminario Technologies LTD

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.SH "SEE ALSO"
.B sg_xcopy, sg_receive_copy_results(sg3_utils)