SG3UTILS SGREQUESTS(1M)
NAME
sgrequests - send one or more SCSI REQUEST SENSE commands
SYNOPSIS
sgrequests [--desc] [--help] [--hex] [--maxlen=LEN]
[--num=NUM] [--progress] [--raw] [--status] [--time] [--ver-
bose] [--version] DEVICE
DESCRIPTION
Send SCSI REQUEST SENSE command to DEVICE and output the
parameter data response which is expected to be in sense
data format. Both fixed and descriptor sense data formats
are supported.
Multiple REQUEST SENSE commands can be sent with the
--num=NUM option. This can be used for timing purposes or
monitoring the progress indication.
OPTIONS
Arguments to long options are mandatory for short options as
well.
-d, --desc
sets the DESC bit in the REQUEST SENSE SCSI cdb. The
DEVICE should return sense data in descriptor (rather
than fixed) format. This will only occur if the DEVICE
recognizes descriptor format (SPC-3 and later). If the
device is pre SPC-3 then setting a bit in a reserved
field may cause a check condition status with an ille-
gal request sense key, but will most likely be ignored.
-h, --help
output the usage message then exit.
-H, --hex
output response in ASCI hexadecimal.
-m, --maxlen=LEN
where LEN is the (maximum) response length in bytes. It
is placed in the cdb's "allocation length" field. If
not given (or LEN is zero) then 252 is used. The max-
imum value of LEN is 255 (but SPC-4 recommends 252).
-n, --num=NUM
perform NUM SCSI REQUEST SENSE commands, stopping when
either NUM is reached or an error occurs. The default
value for NUM is 1 .
-p, --progress
show progress indication (a percentage) if available.
If --number=NUM is given, NUM is greater than 1 and an
initial progress indication was detected then this
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utility waits 30 seconds before subsequent checks.
Exits when NUM is reached or there are no more progress
indications. Ignores --hex, --raw and --time options.
See NOTES section below.
-r, --raw
output response in binary (to stdout).
-s, --status
if the REQUEST SENSE command finished without error (as
indicated by its SCSI status) then the contents of the
parameter data are analysed as sense data and the exit
status is set accordingly. The default action (i.e.
when this option is not given) is to ignore the con-
tents of the parameter data for the purposes of setting
the exit status. Some types of error set a sense key
of "NO SENSE" with non-zero information in the addi-
tional sense code (e.g. the FAILURE PREDICTION THRES-
HOLD EXCEDED group of codes); this results in an exit
status value of 10. If the sense key is "NO SENSE" and
both asc and ascq are zero then the exit status is set
to 0 . See the sg3utils(1M) man page for exit status
values.
-t, --time
time the SCSI REQUEST SENSE command(s) and calculate
the average number of operations per second.
-v, --verbose
increase the level of verbosity, (i.e. debug output).
Additionally the response (if received) is output in
ASCI-HEX. Use this option multiple times for greater
verbosity.
-V, --version
print the version string and then exit.
NOTES
In SCSI 1 and 2 the REQUEST SENSE command was very important
for error and warning processing in SCSI. The autosense
capability rendered this command almost superfluous.
However recent SCSI drafts (e.g. SPC-4 rev 14 and SBC-3 rev
14) increase the utility of the REQUEST SENSE command. Idle
and standby (low) power conditions can be detected with this
command.
The REQUEST SENSE command is not marked as mandatory in
SPC-3 (i.e. for all SCSI devices) but is marked as mandatory
in SBC-2 (i.e. for disks), SC-3 (i.e. for tapes) and MC-4
(i.e. for CD/DVD/HD-DVD/BD drives).
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The progress indication is optionally part of the sense
data. When a prior command that takes a long time to com-
plete (and typically precludes other media access commands)
is still underway, the progress indication can be used to
determine how long before the device returns to its normal
state.
The SCSI FORMAT command for disks used with the IMED bit
set is an example of an operation that takes a significant
amount of time and precludes other media access during that
time. The IMED bit set instructs the FORMAT command to
return control to the application client once the format has
commenced (see SBC-3). Several long duration SCSI commands
associated with tape drives also use the progress indication
(see SC-3).
Early standards suggested that the SCSI TEST UNIT READY com-
mand be used for polling the progress indication. More
recent standards seem to suggest the SCSI REQUEST SENSE com-
mand should be used instead.
EXIT STATUS
The exit status of sgrequests is 0 when it is successful.
Otherwise see the sg3utils(1M) man page.
AUTHORS
Written by Douglas Gilbert.
REPORTING BUGS
Report bugs to .
COPYRIGHT
Copyright O 2004-2008 Douglas Gilbert
This software is distributed under a FreeBSD license. There
is NO warranty; not even for MERCHANTABILITY or FITNES FOR
A PARTICULAR PURPOSE.
SEE ALSO
sg3utils
ATRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
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ATRIBUTE TYPE ATRIBUTE VALUE
Availability SUNWsg3utilsu
Interface Stability Committed
NOTES
Source for sg3utils is available on http:/opensolaris.org.
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