SGINFO(8) SG3_UTILS SGINFO(8)NAMEsginfo - access mode page information for a SCSI (or ATAPI) device
SYNOPSISsginfo [OPTIONS] [DEVICE] [REPLACEMENT_PARAMETERS]
DESCRIPTIONsginfo is a port of the Linux scsiinfo program by Eric Youngdale. It
uses SCSI generic (sg) devices; however in some cases the high level
device name (i.e. sd, sr, st, osst, or hd) can also be used. The pri‐
mary role of this program is to access mode page information. If per‐
mitted, mode page information can be altered. In addition information
from the INQUIRY and READ DEFECTS commands are also available.
Those interested in SCSI mode pages may find the sdparm utility easier
use, especially for changing parameters. Also the author considers this
utility legacy so the mode pages are not being updated as
http://www.t10.org adds and modifies mode page fields.
Four sets of values are maintained by a SCSI device for each mode page:
current (active), default (manufacturer's supplied values), saved (val‐
ues that are retained if the SCSI device is powered down), and change‐
able (mask indicating those values that can be changed). By default
when a mode page is displayed the current values are shown. This can be
overridden by "-M" (defaults), "-S" (saved) or "-m" (modifiable (i.e.
changeable)).
Many mode pages are decoded: for disks (see SBC-2), for CD/DVDs (see
MMC-2/3/4/5), for tapes (see SSC-2) and for enclosures (see SES-2).
Some mode pages common to all SCSI peripheral device types are defined
in SPC-4 (primary commands). A decoded mode page has its field names in
the first column and the corresponding value in the second column. A
"hex" mode page (and subpage) has its byte position in the first column
(in hex and starting at 0x2) and the corresponding hex value in the
second column. Decoded pages can be viewed with the '-t' option or with
a specific option (e.g. 'c' for the caching mode page). Naturally
decoded pages must be supplied by the DEVICE and recognised by this
program. If supported by the device, decoded pages may be modified. All
mode pages (and subpages) that the device supports can be viewed in hex
(and potentially modified) via the "-u" option
If no options are given that will cause mode page(s) or INQUIRY data to
be printed out, then a brief INQUIRY response is output. This includes
the vendor, product and revision level of the device.
OPTIONS-6 Perform 6 byte MODE SENSE and MODE SELECT commands; by default
the 10 byte variants are used.
-a Display some INQUIRY data and the unit serial number followed by
all mode pages reported by the device. It is similar to the '-t
0x3f' option. If the mode page is known then it is output in
decoded form otherwise it is output in hexadecimal.
-A Display some INQUIRY data and the unit serial number followed by
all mode pages and all mode subpages reported by the device. It
is similar to the '-t 0x3f,0xff' option. If a mode (sub)page is
known then it is output in decoded form otherwise it is output
in hexadecimal.
-c Access information in the Caching mode page.
-C Access information in the Control mode Page.
-d Display defect lists (default format: index).
-D Access information in the Disconnect-Reconnect mode page.
-e Access information in the Error Recovery mode page.
-E Access information in the Control Extension mode page.
-f Access information in the Format Device mode page.
-Farg Format of the defect lists:
-Flogical - logical block addresses (32 bit)
-Flba64 - logical block addresses (64 bit)
-Fphysical - physical blocks
-Findex - defect bytes from index
-Fhead - sort by head
Used in conjunction with "-d" or "-G". If a format is not given
"index" is assumed.
-g Access information in the Rigid Disk Drive Geometry mode page.
-G Display grown defect list (default format: index).
-i Display the response to a standard INQUIRY command.
-I Access the Informational Exceptions mode page.
-l List known SCSI devices on the system.
-n Access information in the Notch and Partition mode page.
-N Negate (i.e. stop) mode page changes being placed in the "saved"
page (by default changes go to the current and the saved page).
Only active when used together with '-R'.
-P Access information in the Power Condition mode page.
-r Display all raw (or primary) SCSI device names visible in the
/dev directory. Examples are /dev/sda, /dev/st1 and /dev/scd2.
Does not list sg device names so devices such as a SCSI enclo‐
sure which only have an sg device name are not listed.
-s Display information in the unit serial number page which is a
INQUIRY command variant.
-t PN[,SPN]
Display information from mode page number PN (and optionally sub
page number SPN) in decoded format (if known, otherwise in hex
form). PN is a mode page number in a decimal number from 0 to
63 inclusive. SPN is the mode subpage number and is assumed to
be 0 if not given. SPN is a decimal number from 1 to 255 inclu‐
sive. A page number of 63 returns all pages supported by the
device in ascending order except for page 0 which, if present,
is last. Page 0 is vendor specific and not necessarily in mode
page format. Alternatively hex values can be given for both PN
and SPN (both prefixed by '0x').
-T Trace commands to obtain more verbose output (for debugging).
When used once SCSI commands are shown (in hex) and any errors
from these SCSI commands are spelt out (i.e. with a decoded and
raw sense buffer). When used twice, the additional data sent
with mode select and the response from mode sense are shown (in
hex).
-u PN[,SPN]
Display information from mode page number PN (and optionally
SPN) in hex form. PN is a mode page number in a decimal number
from 0 to 63 inclusive. SPN is the mode subpage number and is
assumed to be 0 if not given. SPN is a decimal number from 1 to
255 inclusive. A page number of 63 returns all pages supported
by the device in ascending order except for page 0 which, if
present, is last. Page 0 is vendor specific and not necessarily
in mode page format. Alternatively hex values can be given for
both PN and SPN (both prefixed by '0x'). For example 63 and 0x3f
are equivalent.
-v Display version string then exit. [N.B. This option increases
verbosity for most other utilities in this package as outlined
in 'man 8 sg3_utils'. This odd usage is for backward compati‐
bility with the scsiinfo utility.]
-V Access information in the Verify Error Recovery mode page. [N.B.
This option prints the version string then exits in most other
utilities in this package as outlined in 'man 8 sg3_utils'. This
odd usage is for backward compatibility with the scsiinfo util‐
ity.]
-z do a single fetch for mode pages (over-estimating the expected
length of the returned response). The default action is to do a
double fetch, the first fetch is to find the response length
that could be returned. Devices that closely adhere to SCSI
standards should not require this option, some real world
devices do require it.
ADVANCED OPTIONS
Only one of the following three options can be specified. None of
these three implies the current values are returned.
-m Display modifiable fields instead of current values
-M Display manufacturer's defaults instead of current values
-S Display saved defaults instead of current values
The following are advanced options, not generally suited for most
users:
-X Display output values in a list. Make them suitable for editing
and being given back to the '-R' (replace command).
\-R Replace parameters - best used with -X (expert use only)
CHANGING MODE PAGE PARAMETERS
Firstly you should know what you are doing before changing existing
parameters. Taking the control page as an example, first list it out
normally (e.g. "sginfo -C /dev/sda") and decide which parameter is to
be changed (note its position relative to the other lines output). Then
execute the same sginfo command with the "-X" option added; this will
output the parameter values in a single row in the same relative posi‐
tions as the previous command. Now execute "sginfo -CXR /dev/sda ..."
with the "..." replaced by the single row of values output by the pre‐
vious command, with the relevant parameter changed. Here is a simpli‐
fied example:
$ sginfo-C /dev/sda
Control mode page (0xa)
-----------------------
TST 0
D_SENSE 0
GLTSD 1
RLEC 0
[Actually the Control page has more parameters that shown above.] Next
output those parameters in single line form:
$ sginfo-CX /dev/sda
0 0 1 0
Let us assume that the GLTSD bit is to be cleared. The command that
will clear it is:
$ sginfo-CXR /dev/sda 0 0 0 0
The same number of parameters output by the "-CX" command needs to be
placed at the end of the "-CXR" command line (after the device name).
Now check that the change took effect:
$ sginfo-C /dev/sda
Control mode page (0xa)
-----------------------
TST 0
D_SENSE 0
GLTSD 0
RLEC 0
When a mode page is "replaced" the default action is to change both the
current page and the saved page. [For some reason versions of sginfo
and scsiinfo prior to 2.0 did not change the "saved" page.] To change
only the current mode page but not the corresponding saved page use the
"-N" option.
GENERATING SCRIPT FILES AND HEX PAGES
The "-aX" or "-AX" option generates output suitable for a script file.
Mode pages are output in list format (after the INQUIRY and serial num‐
ber) one page per line. To facilitate running the output as (part of) a
script file to assert chosen mode page values, each line is prefixed by
"sginfo -t PN[,SPN] -XR ". When such a script file is run, it will have
the effect of re-asserting the mode page values to what they were when
the "-aX" generated the output.
All mode pages (and subpages) supported by the device can be accessed
via the -t and -u options. To see all mode pages supported by the
device use "-u 63". [To see all mode pages and all subpages use "-u
63,255".] To list the control mode page in hex (mode page index in the
first column and the corresponding byte value in the second column) use
"-u 0xa". Mode pages (subpage code == 0) start at index position 2
while subpages start at index position 4. If the "-Xu ..." option is
used then a list a hex values each value prefixed by "@" is output.
Mode (sub)page values can then be modified with with the "-RXu ..."
option.
RESTRICTIONS
The SCSI MODE SENSE command yields block descriptors as well as a mode
page(s). This utility ignores block descriptors and does not display
them. The "disable block descriptor" switch (DBD) in the MODE SENSE
command is not set since some devices yield errors when it is set. When
mode page values are being changed (the "-R" option), the same block
descriptor obtained by reading the mode page (i.e. via a MODE SENSE
command) is sent back when the mode page is written (i.e. via a MODE
SELECT command).
REFERENCES
SCSI (draft) standards can be found at http://www.t10.org . The rele‐
vant documents are SPC-4 (mode pages common to all device types), SBC-2
(direct access devices [e.g. disks]), MMC-4 (CDs and DVDs) and SSC-2
(tapes).
AUTHORS
Written by Eric Youngdale, Michael Weller, Douglas Gilbert, Kurt
Garloff, Thomas Steudten
HISTORY
scsiinfo version 1.0 was released by Eric Youngdale on 1st November
1993. The most recent version of scsiinfo is version 1.7 with the last
patches by Michael Weller. sginfo is derived from scsiinfo and uses the
sg interface to get around the 4 KB buffer limit in scsiinfo that
cramped the display of defect lists especially. sginfo was written by
Douglas Gilbert with patches from Kurt Garloff. This manpage corre‐
sponds with version 2.25 of sginfo.
This software is distributed under the GPL version 2. There is NO war‐
ranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PUR‐
POSE.
SEE ALSOscsiinfo(internet); sg_modes, sg_inq, sg_vpd (sg3_utils),
sdparm(sdparm)sg3_utils-1.34 February 2012 SGINFO(8)
