sg_compare_and_write man page on DragonFly
[printable version]
COMPARE AND WRITE(8) SG3_UTILS COMPARE AND WRITE(8)
NAME
sg_compare_and_write - send the SCSI COMPARE AND WRITE command
SYNOPSIS
sg_compare_and_write [--dpo] [--fua] [--fua_nv] [--help] --in=IF
[--inw=WF] --lba=LBA [--num=NUM] [--quiet] [--timeout=TO] [--verbose]
[--version] [--wrprotect=WP] [--xferlen=LEN] DEVICE
DESCRIPTION
Send the SCSI COMPARE AND WRITE command to DEVICE. This utility reads a
compare buffer and a write buffer from either one or two files. If the
--inw=WF option is not given then the concatenated compare and write
buffers are read from the file indicated by the --in=IF option. If the
--inw=WF option is given then the compare buffer is read from the file
indicated by the --in=IF while the write buffer is read from the file
indicated by the --inw=WF.
Those buffers are expected to each contain NUM blocks of data. The com‐
pare starts at at logical block address LBA on the DEVICE and if the
comparison fails (i.e. the provided compare buffer does not equal at
LBA on the DEVICE) then the COMPARE AND WRITE command finishes with a
sense key of MISCOMPARE. In this case this utility will completes and
set an exit status of 14 (which happens to be the sense key value of
MISCOMPARE).
If the comparison succeeds then the provided write buffer is written to
starting at LBA for NUM blocks on the DEVICE.
The actual number of bytes transferred in the data-out buffer of the
COMPARE AND WRITE command may need to be given by the user with the
--xferlen=LEN option. LEN defaults to (2 * NUM * 512) which is 1024 for
the default NUM of 1. If the block size is other than 512 then the user
will need to use --xferlen=LEN option. If protection information is
given (indicated by a value of WP other than 0 (the default)) then for
a NUM of 1 LEN should be 1040 . Note that the SCSI READ CAPACITY com‐
mand is not checked by this utility (e.g. to find the block size).
The definition of the SCSI COMPARE AND WRITE command requires that the
DEVICE implement the compare and optional write as an uninterrupted
series of actions. Depending on some other DEVICE settings a verify
operation may occur prior to the compare.
When a mismatch occurs between the compare buffer and the blocks start‐
ing at LBA read from the DEVICE the sense buffer containing the MISCOM‐
PARE sense key causes several messages to be sent to stderr (including
the offset of the first byte mismatch). To suppress these messages use
the --quiet option. With or without the --quiet option the exit status
will be set to 14.
This command is defined in SBC-3 whose most recent revision is 36.
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. This will either be the
combined compare and write buffers (when the --inw=WF option is
not given) or just the compare buffer (when the --inw=WF option
is given). If IF is '-' then stdin (e.g. a pipe) is read.
-D, --inw=WF
read data (binary) from file named WF. This will the write buf‐
fer that will become the second half of the data-out buffer sent
to the DEVICE associated with the COMPARE AND WRITE command.
Note that when this option is given then the --in=IF is expected
to hold the associated compare buffer.
-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.
-q, --quiet
suppress the sense buffer messages associated with a MISCOMPARE
sense key that would otherwise be sent to stderr. Still set the
exit status to 14 which is the sense key value indicating a MIS‐
COMPARE.
-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 com‐
mand may require considerably more time than 60 seconds to com‐
plete.
-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 in byte. It defaults to
(2 * NUM * 512) bytes. If the DEVICE block size is other than
512 bytes or WP is non-zero (implying additional protection
information) then this default will be incorrect; the use must
supply the correct value for LEN
NOTES
Various numeric arguments (e.g. LBA) may include multiplicative suf‐
fixes 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. If
the compare step fails then the exit status is 14. For other exit sta‐
tus values see the EXIT STATUS section in the sg3_utils(8) man page.
Earlier versions of this utility set an exit status of 98 when there
was a MISCOMPARE.
AUTHORS
Written by Shahar Salzman. Maintained by Douglas Gilbert. Additions by
Eric Seppanen.
REPORTING BUGS
Report bugs to shahar.salzman@kaminario.com or dgilbert@interlog.com
COPYRIGHT
Copyright © 2012-2014 Kaminario Technologies LTD
Redistribution and use in source and binary forms, with or without mod‐
ification, 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 contribu‐
tors may be used to endorse or promote products derived from this soft‐
ware 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 PARTIC‐
ULAR 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 BUSI‐
NESS 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-1.38 March 2014 COMPARE AND WRITE(8)
[top]
List of man pages available for DragonFly
Copyright (c) for man pages and the logo by the respective OS vendor.
For those who want to learn more, the polarhome community provides shell access and support.
[legal]
[privacy]
[GNU]
[policy]
[cookies]
[netiquette]
[sponsors]
[FAQ]
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
....................................................................
|
|
Vote for polarhome
|
