sg_bg_ctl - send SCSI BACKGROUND CONTROL command
sg_bg_ctl [--ctl=CTL] [--help] [--time=TN] [--verbose] [--version] DEVICE
SG_BG_CTL(8) SG3_UTILS SG_BG_CTL(8)
NAME
sg_bg_ctl - send SCSI BACKGROUND CONTROL command
SYNOPSIS
sg_bg_ctl [--ctl=CTL] [--help] [--time=TN] [--verbose] [--version]
DEVICE
DESCRIPTION
Sends a SCSI BACKGROUND CONTROL command to the DEVICE. This command was
first found in the SBC-4 draft standard revision 8 (sbc4r08.pdf). It
can be used to start and stop 'advanced background operations' on the
DEVICE. Only resource or thin provisioned devices (logical units which
are typically (solid state) disks) support this command. Those advanced
background operations often include garbage collection type operations
which may degrade the disk's performance while they are being per-
formed.
OPTIONS
Arguments to long options are mandatory for short options as well.
-c, --ctl=CTL
CTL is the value placed in the BO_CTL field of the BACKGROUND
CONTROL command (cdb). It is a two bit field so has 4 variants:
0 does not change the host initiated advanced background opera-
tions; 1 starts these operations; 2 stops these operations and 3
is reserved. The default value is 0.
-h, --help
output the usage message then exit.
-t, --time=TN
TN is a maximum time (with a unit of 100 ms or 1/10 second) that
advanced background operations can occur. This value is ignored
if the CTL argument is other than 1. The default value is 0
which means there is no maximum time limit. Only values 0 to 255
(which is 25.5 seconds) can be given. This value is place in the
BO_TIME field of the BACKGROUND CONTROL command.
-v, --verbose
increase the level of verbosity, (i.e. debug output).
-V, --version
print the version string and then exit.
ATTRIBUTES
See attributes(7) for descriptions of the following attributes:
+---------------+--------------------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+--------------------------+
|Availability | system/storage/sg3_utils |
+---------------+--------------------------+
|Stability | Pass-through uncommitted |
+---------------+--------------------------+
NOTES
According to T10, support for 'background control operations' is indi-
cated by the BOCS bit being set in the Block device characteristics VPD
page [0xb1]. The setting of the BOCS bit can be checked with the
sg_vpd and sdparm utilities (and it is read only). There is a Back-
ground operations control mode page [0xa, 0x6] with a BO_MODE field for
modifying the action of this operation. The BO_MODE field can be
accessed and possibly modified with the sdparm utility. The BO_STATUS
field can be found in the Background operation log page [0x15, 0x2] and
that can be viewed with the sg_logs utility.
The current draft describing this area is SBC-4 revision 10
(sbc4r10.pdf) in clause 4.33 . That contains the following example of a
background operation: "Advanced background operation may include NAND
block erase operations, media read operations, and media write opera-
tions (e.g., garbage collection), which may impact response time for
normal read requests or write requests from the application client."
Source code for open source software components in Oracle Solaris can
be found at https://www.oracle.com/downloads/opensource/solaris-source-
code-downloads.html.
This software was built from source available at
https://github.com/oracle/solaris-userland. The original community
source was downloaded from http://sg.danny.cz/sg/p/sg3_utils-1.46.tgz.
Further information about this software can be found on the open source
community website at http://sg.danny.cz/sg/sg3_utils.html.
EXIT STATUS
The exit status of sg_bg_ctl is 0 when it is successful. Otherwise see
the sg3_utils(8) man page.
AUTHORS
Written by Douglas Gilbert.
REPORTING BUGS
Report bugs to <dgilbert at interlog dot com>.
COPYRIGHT
Copyright (C) 2016 Douglas Gilbert
This software is distributed under a FreeBSD license. There is NO war-
ranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PUR-
POSE.
SEE ALSO
sg_vpd,sg_logs(sg3_utils); sdparm(sdparm)
sg3_utils-1.43 May 2016 SG_BG_CTL(8)