sg_sat_identify (8)

sg_sat_identify [--ck_cond] [--extend] [--help] [--hex] [--indent] [--len={16|12}] [--packet] [--raw] [--readonly] [--verbose] [--version] DEVICE

This utility sends either an ATA IDENTIFY DEVICE command or an ATA IDENTIFY PACKET DEVICE command to DEVICE and outputs the response. The devices that respond to these commands are ATA disks and ATAPI devices respectively. Rather than send these commands directly to the device they are sent via a SCSI transport which is assumed to contain a SCSI to ATA Translation (SAT) Layer (SATL). The SATL may be in an operating system driver, in host bus adapter firmware or in some external enclosure.

The SAT standard (SAT ANSI INCITS 431-2007, prior draft: sat-r09.pdf at www.t10.org) defines two SCSI "ATA PASS-THROUGH" commands: one using a 16 byte "cdb" and the other with a 12 byte cdb. This utility defaults to using the 16 byte cdb variant. SAT-2 is also a standard: SAT-2 ANSI INCITS 465-2010 and the draft prior to that is sat2r09.pdf . The SAT/-3 project has started and the most recent draft is sat3r01.pdf .

Arguments to long options are mandatory for short options as well.

-c, --ck_cond

sets the CK_COND bit in the ATA PASS-THROUGH SCSI cdb. The default setting is clear (i.e. 0). When set the SATL should yield a sense buffer containing a ATA Result descriptor irrespective of whether the command succeeded or failed. When clear the SATL should only yield a sense buffer containing a ATA Result descriptor if the command failed.

-e, --extend

sets the EXTEND bit in the ATA PASS-THROUGH SCSI cdb. The default setting is clear (i.e. 0). When set a 48 bit LBA command is sent to the device. This option has no effect when --len=12.

-h, --help

outputs the usage message summarizing command line options then exits. Ignores DEVICE if given.

-H, --hex

outputs the ATA IDENTIFY (PACKET) DEVICE response in hex. The default action (i.e. without any '-H' options) is to output the response in hex, grouped in 16 bit words (i.e. the ATA standard's preference). When given once, the response is output in ASCII hex bytes (i.e. the SCSI standard's preference). When given twice (i.e. '-HH') the output is in hex, grouped in 16 bit words, the same as the default but without a header. When given thrice (i.e. '-HHH') the output is in hex, grouped in 16 bit words, in a format that is acceptable for 'hdparm --Istdin' to process.

-i, --indent

outputs the World Wide Name (WWN) of the device. This should be a NAA-5 64 bit number. It is output in hex prefixed with "0x". If not available then "0x0000000000000000" is output. The equivalent for a SCSI disk (i.e. its logical unit name) can be found with "sg_vpd -ii".

-l, --len={16|12}

this is the length of the SCSI cdb used for the ATA PASS-THROUGH commands. The argument can either be 16 or 12. The default is 16. The larger cdb size is needed for 48 bit LBA addressing of ATA devices. On the other hand some SCSI transports cannot convey SCSI commands longer than 12 bytes.

-p, --packet

send an ATA IDENTIFY PACKET DEVICE command (via the SATL). The default action is to send an ATA IDENTIFY DEVICE command.

-r, --raw

output the ATA IDENTIFY (PACKET) DEVICE response in binary. The output should be piped to a file or another utility when this option is used. The binary is sent to stdout, and errors are sent to stderr.

-R, --readonly

open the DEVICE read-only (e.g. in Unix with the O_RDONLY flag). The default is to open it read-write.

-v, --verbose

increases the level or verbosity.

-V, --version

print out version string

Since the response to the IDENTIFY (PACKET) DEVICE command is very important for the correct use of an ATA(PI) device (and is typically the first command sent), a SATL should provide an ATA Information VPD page which contains the similar information.

The SCSI ATA PASS-THROUGH (12) command's opcode is 0xa1 and it clashes with the MMC set's BLANK command used by cd/dvd writers. So a SATL in front of an ATAPI device that uses MMC (i.e. has peripheral device type 5) probably should treat opcode 0xa1 as a BLANK command and send it through to the cd/dvd drive. The ATA PASS-THROUGH (16) command's opcode (0x85) does not clash with anything so it is a better choice.

In the 2.4 series of Linux kernels the 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"). Prior to lk 2.6.29 USB mass storage limited sense data to 18 bytes which made the --ck_cond option yield strange (truncated) results.

The exit status of sg_sat_identify is 0 when it is successful. Otherwise see the sg3_utils(8) man page.

Written by Douglas Gilbert

Report bugs to <dgilbert at interlog dot com>.

Copyright © 2006-2013 Douglas Gilbert

This software is distributed under a FreeBSD license. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

sg_vpd(sg3_utils), sg_inq(sg3_utils), sdparm(sdparm), hdparm(hdparm)