SG_SAT_SET_FEATURES(8)

NAME
sg_sat_set_features - sends a ATA SET FEATURES command via a SCSI to ATA Translation (SAT) layer

SYNOPSIS
sg_sat_set_features [--count=CO] [--chk_cond] [--feature=FEA] [--help] [--len=16|12] [--lba=LBA] [--verbose] [--version] DEVICE

DESCRIPTION

This utility sends an ATA SET FEATURES command to the DEVICE. This command is used to change settings of ATA non-packet (i.e. disks) and packet devices (e.g. cd/dvd drives). Rather than send the SET FEATURES command directly to the device it is sent via a SCSI transport which is assumed to contain a SCSI to ATA Translation (SAT) Layer (SATL). 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 the 16 byte cdb variant.

The SATL may be in an operating system driver, in host bus adapter firmware or in some external enclosure.

The features can be read using the sg_sat_identify utility which uses either the ATA IDENTIFY DEVICE (for non-packet devices) or the IDENTIFY PACKET DEVICE (for packet devices) command.

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

-c, --count=CO
    the number CO is placed in the "count" field in the ATA SET FEATURES command. Only some subcommands (a term used for the value placed in the "feature" field) require the count field to be set. The default value placed in the "count" field is 0.

-C, --chk_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 ATA command succeeded or failed. When clear the SATL should only yield a sense buffer containing a ATA Result descriptor if the ATA command failed.

-f, --feature=FEA
    the value FEA is placed in the "feature" field in the ATA SET FEATURES command. The term "subcommand" is sometimes used for this value. The default value placed in the "feature" field is 0 which is reserved and hence should not change anything. Two common examples are 2h to enable the write cache and 82h to disable it.

-h, --help
    outputs the usage message summarizing command line options then exits. Ignores DEVICE if given.

-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. Some SCSI transports cannot convey SCSI commands longer than 12 bytes.

-L, --lba=LBA
    the number LBA is placed in the "lba" field in the ATA SET FEATURES command. Only some subcommands (a term used for the value placed in the "feature" field) require the lba field to be set. This value is not a "logical block address" as the acronym might imply. The default value placed in the "lba" field is 0.

-v, --verbose
    increases the level or verbosity.

-V, --version
    print out version string

NOTES
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").

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

AUTHOR
Written by Doug Gilbert

REPORTING BUGS
Report bugs to <dgilbert at interlog dot com>.

COPYRIGHT
Copyright © 2007 Douglas Gilbert
This software is distributed under a FreeBSD license. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

SEE ALSO
sg_sat_identify(sg3_utils), sg_inq(sg3_utils), sdparm(sdparm), hdparm(hdparm)