SG_SCAN(8) SG3_UTILS SG_SCAN(8)
NAME
sg_scan - scans sg devices (or SCSI/ATAPI/ATA devices) and prints results
SYNOPSIS
sg_scan [-a] [-i] [-n] [-w] [-x] [DEVICE]*
DESCRIPTION
If no DEVICE names are given, sg_scan does a scan of the sg devices and outputs a line of information for each sg device that is currently
bound to a SCSI device. If one or more DEVICEs are given only those devices are scanned. Each device is opened with the O_NONBLOCK flag so
that the scan will not "hang" on any device that another process holds an O_EXCL lock on.
Any given DEVICE name is expected to comply with (to some extent) the Storage Architecture Model (SAM see www.t10.org). Any device names
associated with the Linux SCSI subsystem (e.g. /dev/sda and /dev/st0m) are suitable. Devices names associated with ATAPI devices (e.g. most
CD/DVD drives and ATAPI tape drives) are also suitable. If the device does not fall into the above categories then an ATA IDENTIFY command
is tried.
In Linux 2.6 and 3 series kernels, the lsscsi utility may be helpful. Apart from providing more information (by data-mining in the sysfs
pseudo file system), it does not need root permissions to execute, as this utility would typically need.
OPTIONS
-a do alphabetical scan (i.e. sga, sgb, sgc). Note that sg device nodes with an alphabetical index have been deprecated since the Linux
kernel 2.2 series.
-i do a SCSI INQUIRY, output results in a second (indented) line. If the device is an ATA disk then output information from an ATA
IDENTIFY command
-n do numeric scan (i.e. sg0, sg1...) [default]
-w use a read/write flag when opening sg device (default is read-only)
-x extra information output about queuing
NOTES
This utility was written at a time when hotplugging of SCSI devices was not supported in Linux. It used a simple algorithm to scan sg
device nodes in ascending numeric or alphabetical order, stopping after there were 4 consecutive errors.
In the Linux kernel 2.6 series, this utility uses sysfs to find which sg device nodes are active and only checks those. Hence there can be
large "holes" in the numbering of sg device nodes (e.g. after an adapter has been removed) and still all active sg device nodes will be
listed. This utility assumes that sg device nodes are named using the normal conventions and searches from /dev/sg0 to /dev/sg4095 inclu-
sive.
EXIT STATUS
The exit status of sg_scan is 0 when it is successful. Otherwise see the sg3_utils(8) man page.
AUTHORS
Written by D. Gilbert and F. Jansen
COPYRIGHT
Copyright (C) 1999-2013 Douglas Gilbert
This software is distributed under the GPL version 2. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PUR-
POSE.
SEE ALSO
lsscsi(8)
sg3_utils-1.36 May 2013 SG_SCAN(8)
