sg_sat_identify - Man Page

sg_sat_identify [--ck_cond] [--extend] [--help] [--hex] [--ident] [--len=CLEN] [--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-4 revision 5 added a SCSI "ATA PASS-THROUGH(32)" command. SAT-2 and SAT-3 are now also standards: SAT-2 ANSI INCITS 465-2010 and SAT-3 ANSI INCITS 517-2015 . The SAT-4 project is near standardization and the most recent draft is sat4r06.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. '-HHHH' simply outputs hex data bytes, space separated, 16 per line.

-i,  --ident

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=CLEN

CLEN this is the length of the SCSI cdb used for the ATA PASS-THROUGH command.  CLEN can either be 12, 16 or 32. The default is 16. The larger cdb sizes are needed for 48 bit LBA addressing of ATA devices. The ATA Auxiliary and ICC registers are only conveyed with the 32 byte cdb variant.

-p,  --packet

send an ATA IDENTIFY PACKET DEVICE command (via the SATL). The default action is to send an ATA IDENTIFY DEVICE command. Note that the ATAPI specification by T13 (i.e. the PACKET interface) is now obsolete.

-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.

Prior to Linux kernel 2.6.29 USB mass storage limited sense data to 18 bytes which made the --ck_cond option yield strange (truncated) results.

These examples use Linux device names and a Linux utility called hdparm. For suitable device names in other supported Operating Systems see the sg3_utils(8) man page.

In this example /dev/sdb is a SATA 2.5" disk connected via a USB (type C connector) dongle that implements the UAS (USB attached SCSI) protocol (also known as UASP). UAS is a vast improvement over the USB mass storage class.

   # sg_sat_identify /dev/sdb
   Response for IDENTIFY DEVICE ATA command:
   00   0c5a 3fff c837 0010 0000 0000 003f 0000  .Z ?. .7 .. .. .. .? ..
....

The hexadecimal ASCII (with plain ASCII to the right) output is abridged to a single line (i.e. the first 16 bytes (or 8 words)). Now to decode some of that ATA Identify response. First sg_inq can decode a few strings:

   # sg_sat_identify -HHHH /dev/sdb | sg_inq --ata -I -
   ATA device: model, serial number and firmware revision:
   ST9500420AS     5VJCE6R7 0002SDM1

For a lot more details, the hdparm utility is a good choice:

   # sg_sat_identify -HHH /dev/sdb | hdparm --Istdin
   ATA device, with non-removable media
       Model Number:       ST9500420AS
       Serial Number:      5VJCE6R7
       Firmware Revision:  0002SDM1
       Transport:          Serial
   Standards:
   ....

There are about 80 more lines of details decoded by hdparm in this case. Notice the difference in the number of "H" options: three give an unadorned hex output arranged in (little endian) words (i.e. 16 bits each) while four "H" options give an unadorned hex output in bytes (i.e. 8 bits each).

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 © 2006-2020 Douglas Gilbert
This software is distributed under a BSD-2-Clause 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)