sg_decode_sense man page on DragonFly
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SG_DECODE_SENSE(8) SG3_UTILS SG_DECODE_SENSE(8)
NAME
sg_decode_sense - decode SCSI sense data
SYNOPSIS
sg_decode_sense [--binary=FN] [--file=FN] [--help] [--hex] [--nospace]
[--status=SS] [--verbose] [--version] [--write=WFN] [H1 H2 H3 ...]
DESCRIPTION
This utility takes SCSI sense data in binary or as a sequence of ASCII
hexadecimal bytes and decodes it. The primary reference for the decod‐
ing is SPC-3 ANSI INCITS 408-2005 and the most recent draft SPC-4 revi‐
sion 37 which can be found at http://www.t10.org and other locations on
the internet.
SCSI sense data is often found in kernel log files as a result of some‐
thing going wrong but may just be informative. It is often shown as a
sequence of hexadecimal bytes, starting with 70, 71, 72, 73, f0 or f1.
Sense data could be up to 252 bytes long but typically is much shorter
than that, 18 bytes long is often seen and is usually associated with
the older "fixed" format sense data.
The sense data can be provided on the command line or in a file. If
given on the command line the sense data should be a sequence of hexa‐
decimal bytes separated by space. Alternatively a file can be given
with the contents in binary or ASCII hexadecimal bytes. The latter form
can contain several lines each with none, one or more ASCII hexadecimal
bytes separated by space (comma or tab). The hash symbol may appear and
it and the rest of the line is ignored making it useful for comments.
OPTIONS
Arguments to long options are mandatory for short options as well.
-b, --binary=FN
the sense data is read in binary from a file called FN.
-h, --help
output the usage message then exit.
-H, --hex
this option is used in conjunction with --write=WFN in order to
change the output written to WFN to lines of ASCII hex bytes
suitable for a C language compiler. Each line contains up to 16
bytes (e.g. a line starting with "0x3b,0x07,0x00,0xff").
-f, --file=FN
the sense data is read in ASCII hexadecimal from a file called
FN. The sense data should appear as a sequence of bytes sepa‐
rated by space, comma, tab or newline. Everything from and
including a hash symbol to the end of that line is ignored. If
--nospace is set then no separator is required between the ASCII
hexadecimal digits in FN with bytes decoded from pairs of ASCII
hexadecimal digits.
-n, --nospace
expect ASCII hexadecimal to be a string of hexadecimal digits
with no spaces between them. Bytes are decoded by taking two
hexadecimal digits at a time, so an even number of digits is
expected. The string of hexadecimal digits may be on the command
line (replacing "H1 H2 H3") or spread across multiple lines the
FN given to --file=. On the command line, spaces (or other
whitespace characters) between sequences of hexadecimal digits
are ignored; the maximum command line hex string is 1023 charac‐
ters long.
-s, --status=SS
where SS is a SCSI status byte value, given in hexadecimal. The
SCSI status byte is related to but distinct from sense data.
-v, --verbose
increase the degree of verbosity (debug messages).
-V, --version
output version string then exit.
-w, --write=WFN
writes the sense data out to a file called WFN. If necessary WFN
is created. If WFN exists then it is truncated prior to writing
the sense data to it. If the --hex option is also given then
ASCII hex is written to WFN (see the --hex option description);
otherwise binary is written to WFN. This option is a convenience
and may be helpful in converting the ASCII hexadecimal represen‐
tation of sense data (or anything else) into the equivalent
binary or a compilable ASCII hex form.
NOTES
Unlike most utilities in this package, this utility does not access a
SCSI device (logical unit). This utility accesses a library associated
with this package. Amongst other things the library decodes SCSI sense
data.
T10 defined SCSI command names given a CDB can be decoded using the
sg_raw utility with the '-vvv' option.
EXAMPLES
Sense data is often printed out in kernel logs and sometimes on the
command line when verbose or debug flags are given. It will be at least
8 bytes long, often 18 bytes long but may be longer. A sense data
string might look like this:
f0 00 03 00 00 12 34 0a 00 00 00 00 11 00 00 00
00 00
Cut and paste it after the sg_decode_sense command:
sg_decode_sense f0 00 03 00 00 12 34 0a 00 00 00 00 11 00 00 00 00 00
and for this sense data the output should look like this:
Fixed format, current; Sense key: Medium Error
Additional sense: Unrecovered read error
Info fld=0x1234 [4660]
For a medium error the Info field is the logical block address (LBA) of
the lowest numbered block that the associated SCSI command was not able
to read (verify or write).
EXIT STATUS
The exit status of sg_decode_sense is 0 when it is successful. Other‐
wise see the sg3_utils(8) man page.
AUTHORS
Written by Douglas Gilbert.
REPORTING BUGS
Report bugs to <dgilbert at interlog dot com>.
COPYRIGHT
Copyright © 2010-2014 Douglas Gilbert
This software is distributed under a FreeBSD license. There is NO war‐
ranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PUR‐
POSE.
SEE ALSO
sg_requests,sg_raw(sg3_utils)
sg3_utils-1.40 August 2014 SG_DECODE_SENSE(8)
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