http://man-wiki.net/index.php/8:sg_inq
sg_inq - outputs data retrieved from the SCSI INQUIRY or ATA IDENTIFY (PACKET) DEVICE command
SYNOPSIS
sg_inq [-a] [-A] [-b] [-c] [-cl] [-d] [-e] [-h] [-H] [-i] [-m] [-m] [-o=<opcode_page>] [-p=<vpd_page>] [-P] [-r]
[-s] [-v] [-V] [-x] [-36] [-?] <device>
DESCRIPTION
This utility by default sends an INQUIRY SCSI command to the given device and then outputs the response. All SCSI
devices are meant to respond to a "standard" INQUIRY command with at least a 36 byte response (in SCSI 2 and
higher). An INQUIRY is termed as "standard" when both the EVPD and CmdDt bits are clear.
An important "non-standard" INQUIRY page is the Device Identification Vital Product Data (VPD) page (page number:
0x83). Since SPC-3, support for this page has been flagged as mandatory. The '-i' option decodes this page.
If <device> exists and the SCSI INQUIRY fails (because the SG_IO ioctl is unknown) then an ATA IDENTIFY (PACKET)
DEVICE is tried. If it succeeds then device identification strings are output. If the "-r" option is given then
the 512 byte IDENTIFY response is output in binary. If the "-H" (or "-h") option is given then the 512 byte
response is output in ASCII hex, grouped as 256 16 bit words, 8 words per line. If the "-A" option is given then
the SCSI INQUIRY is not performed and the device is assumed to be ATA (or ATAPI). This allows ATAPI transport
information to be found for ATAPI cd/dvd drives; since without this option such drives respond to a SCSI INQUIRY
command.
The reference document used for interpreting an INQUIRY is T10/1713-D Revision 4 (SPC-4, 9 March 2006) found at
http://www.t10.org . Obsolete items in the standard INQUIRY response are displayed in brackets. The reference
document for the ATA IDENTIFY (PACKET) DEVICE command is ATA8-ACS found at http://www.t13.org .
ATA or ATAPI devices that use a SCSI to ATA Translation layer (see SAT at www.t10.org) may support the ATA Infor-
mation VPD page. This returns the IDENTIFY (PACKET) DEVICE response amongst other things. See the '-a' option.
-a decodes the ATA Information Vital Product Data (VPD) page [0x89]. If '-H' is given then the whole page as
ASCII hex bytes; with '-HH' the IDENTIFY (PACKET) DEVICE response is output in ASCII hex bytes; and with-
out either the IDENTIFY (PACKET) DEVICE response is output in 16 bit ASCII hex words. This page is defined
in SAT (revision 5) at www.t10.org .
-A Assume given <device> is an ATA or ATAPI device which can receive ATA passthrough commands from the host
operating system. Skip the SCSI INQUIRY command and use either the ATA IDENTIFY DEVICE command (for non-
packet devices) or the ATA IDENTIFY PACKET DEVICE command. This option is not available in the FreeBSD
port.
-b decodes the Block Limits Vital Product Data (VPD) page [0xb0]. This page is defined in SBC-2 (revision
16) at www.t10.org .
-c set the Command Support Data (CmdDt) bit (defaults to clear(0)). Used in conjunction with the
'-o=<opcode>' option to specify the SCSI command opcode to supply the support data for. The command sup-
port data is a mask of the same length as the command with bits set in positions that are modifiable. For
example, '12 03 ff 00 ff 01' shows the device supports the EVPD and CmdDt bits [byte 1, bits 0 and 1] in
an INQUIRY command. The CmdDt bit is now obsolete. It has been replaced by the REPORT SUPPORTED OPERATION
CODES command which is accessed via the sg_opcodes utility.
-cl lists the command data for all supported commands (followed by the command name) by looping through all
256 opcodes. This option uses the CmdDt bit which is now obsolete. See the sg_opcodes utility.
-d decodes depending on context. If '-e' option is given, or any option that implies '-e' (e.g. '-i' or
'-p=80'), then this utility attempts to decode the indicated VPD page. Otherwise the version descriptors
(if any) are listed following a standard INQUIRY response. There are up to 8 version descriptors in the
response of a standard INQUIRY, If the version descriptor code is recognised then the corresponding string
is output. Version descriptors are versions of standards and drafts that the device claims to comply with
(e.g. SAM, SPC, SBC, SPI, FCP, SAS etc).
-e enable (i.e. sets) the Vital Product Data (EVPD) bit (defaults to clear(0)). Used in conjunction with the
'-p=<vpd_page>' option to specify the VPD page to fetch. If '-p' is not given then VPD page 0 (list
supported VPD pages) is assumed. Support for VPD page 0 and page 0x83 (device identification) have been
made mandatory in SPC-3 .
-h outputs INQUIRY response in hex rather than trying to decode it. When used with '-i' outputs partially
decoded device identification descriptors with the identifier itself output in hex. When selected, ATA
IDENTIFY responses are output in 16 bit words if '-h' is given; they are output in bytes when '-hh' (or
'-HH') is given. The '-hh' option has a similar effect on the ATA information VPD page decoding (i.e. when
the '-a' option is given).
-H same action as "-h". For compatibility with many other sg3_utils programs in which "-H" is for hex output.
-i decodes the Device Identification Vital Product Data (VPD) page [0x83]. This page is made up of several
"identification descriptors". If '-h' is given then each descriptor header is decoded and the identifier
itself is output in hex. To see the whole VPD 0x83 page response in hex use '-p=83 -h'. Since SPC-3, sup-
port for the device identification VPD page is mandatory.
-m decodes the Management network addresses Vital Product Data (VPD) page [0x85]. This page is made up of
several "network service descriptors". If '-h' is given then each descriptor payload is output in hex.
-M decodes the Mode page policy Vital Product Data (VPD) page [0x87]. This page is made up of several "mode
page policy descriptors". If '-h' is given then each descriptor payload is output in hex.
-o=<opcode_page>
used in conjunction with the '-e' or '-c' option. If neither given then the '-e' option assumed. When the
'-e' option is also given (or assumed) then the argument to this option is the VPD page number. The argu-
ment is interpreted as hexadecimal and is expected to be in the range 0 to ff inclusive. Only VPD page 0
is decoded and lists supported VPD pages and their names (if known). To decode the mandatory device iden-
tification page (0x83) use the '-i' option. A now obsolete usage is when the '-c' option is given in
which case the argument to this option is assumed to be a command opcode number. Recent SCSI draft stan-
dards have moved this facility (see sg_opcodes). Defaults to 0 so if '-e' is given without '-o=' then VPD
page 0 is output.
-p=<vpd_page>
same action as '-o=<opcode_page>' option described above. Since the opcode value with the CmdDt is now
obsolete, the main use of this option is to specify the VPD page number. The argument is interpreted as
hexadecimal and is expected to be in the range 0 to ff inclusive. Defaults to 0 so if '-e' is given with-
out '-p=' then VPD page 0 is output.
-P decodes the Unit Path Report Vital Product Data (VPD) page [0xc0], which is specific to selected EMC
devices. To see the whole VPD 0xc0 page response in hex use '-p=c0 -h'.
-r outputs the INQUIRY response in binary. If the SCSI INQUIRY has failed and an ATA IDENTIFY succeeds then
the 512 bytes of the IDENTIFY response is output in binary. Overrides the various VPD decoding options.
Standard output should be redirected to a file or some other program that can process binary data. Can be
used twice and if used with the '-A' or '-a' option yields output with the same format as "cat
/proc/ide/hd<x>/identify" so that it can then be piped to "hdparm --Istdin".
-s decodes the SCSI Ports Vital Product Data (VPD) page [0x88]. The response contains information about the
target (or rarely the initiator) ports associated with the addressed device server (i.e. the target). In
practice this is a way to find all target port addresses of a dual ported disk. If '-h' is given then
each target (and/or initiator) descriptor is output in hex. To see the whole VPD 0x88 page response in hex
use '-p=88 -h'.
-v verbose: print out cdb of issued commands prior to execution. '-vv' and '-vvv' are also accepted yielding
greater verbosity. For ATA disks the identity response (256 16 bit words) is output when this option is
given.
-V print out version string
-x decodes the Extended INQUIRY data Vital Product Data (VPD) [0x86] page. If '-h' is given then prints out
VPD page in hex which is similar to using '-p=86 -h'.
-36 only requests 36 bytes of response data for an INQUIRY. Furthermore even if the device indicates in its
response it can supply more data, a second (longer) INQUIRY is not performed. This is a paranoid setting.
-? output usage message and exit. Ignore all other parameters.
Some devices with weak SCSI command set implementations lock up when they receive commands they don't understand
(or even response lengths that they don't expect). Such devices need to be treated carefully, hence the '-36'
option. Without this option this utility will issue an initial standard INQUIRY requesting 36 bytes of response
data. If the device indicates it could have supplied more data then a second INQUIRY is issued to fetch the
longer response. That second command may lock up faulty devices.
In the INQUIRY standard response there is a 'MultiP' flag which is set when the device has 2 or more ports. Some
vendors use the preceding vendor specific ('VS') bit to indicate which port is being accessed by the INQUIRY com-
mand (0 -> relative port 1 (port "a"), 1 -> relative port 2 (port "b")). When the 'MultiP' flag is set, the pre-
ceding vendor specific bit is shown in parentheses. SPC-3 compliant devices should use the device identification
VPD page (0x83) to show which port is being used for access and the SCSI ports VPD page (0x88) to show all avail-
able ports on the device.
In the 2.4 series of Linux kernels the given device must be a SCSI generic (sg) device. In the 2.6 series block
devices (e.g. disks and ATAPI DVDs) can also be specified. For example "sg_inq /dev/sda" will work in the 2.6
series kernels. From lk 2.6.6 other SCSI "char" device names may be used as well (e.g. "/dev/st0m").
ATA DEVICES
There are two major types of ATA devices: non-packet devices (e.g. ATA disks) and packet devices (ATAPI). The
majority of ATAPI devices are CD/DVD drives in which the ATAPI transport carries the MMC set (i.e. a SCSI com-
mand set). Further, both types of ATA devices can be connected to a host computer via a "SCSI" (or some other)
transport. When an ATA disk is controlled via a SCSI (or non-ATA) transport then two approaches are commonly
used: tunnelling (e.g. STP in Serial Attached SCSI (SAS)) or by emulating a SCSI device (typically via a SCSI to
ATA translation layer, see SAT at www.t10.org ). Even when the physical transport to the host computer is ATA
(especially in the case of SATA) the linux operating system may choose to put a SAT layer in the driver "stack"
(e.g. libata).
The main identifying command for any SCSI device is an INQUIRY. The corresponding command for an ATA non-packet
device is IDENTIFY DEVICE while for an ATA packet device it is IDENTIFY PACKET DEVICE.
When this utility is invoked for an ATAPI device (e.g. a CD/DVD drive with "sg_inq /dev/hdc") then a SCSI INQUIRY
is sent to the device and if it responds then the response to decoded and output and this utility exits. To see
the response for an ATA IDENTIFY PACKET DEVICE command add the '-A' option (e.g. "sg_inq -A /dev/hdc) and to see
the response in hex add the "-H" option as well (e.g. "sg_inq -A -H /dev/hdc").
This utility doesn't decode the response to an ATA IDENTIFY (PACKET) DEVICE command, hdparm does a good job at
that. The '-rr' option has been added to use with either the '-A' or '-a' option to produce a format acceptable
to "hdparm --Istdin". See hdparm.
EXIT STATUS
The exit status of sg_inq is 0 when it is successful. Otherwise see the sg3_utils(8) man page.
REPORTING BUGS
Report bugs to <dgilbert at interlog dot com>.
COPYRIGHT
Copyright ? 2001-2006 Douglas Gilbert
This software is distributed under the GPL version 2. There is NO warranty; not even for MERCHANTABILITY or FIT-
NESS FOR A PARTICULAR PURPOSE.
RELATED
sgdiag(scsirastools), sg_opcodes(sg3_utils), sg_modes(sg3_utils), sg_logs(sg3_utils), hdparm(hdparm),
sg_vpd(sg_vpd)
