path: root/sg_start.8

.TH SG_START "8" "April 2006" "sg3_utils-1.20" SG3_UTILS
.SH NAME
sg_start \- starts (spins-up) or stops (spins down) device, load or
eject medium
.SH SYNOPSIS
.B sg_start
[\fI--eject\fR] [\fI--fl=<n>\fR] [\fI-i\fR] [\fI--imm=0|1\fR] [\fI--load\fR]
[\fI--loej\fR] [\fI--pc=<n>\fR] [\fI--start\fR] [\fI--stop\fR] [\fI-v\fR]
[\fI-V\fR] [\fI0|1\fR] \fI<device>\fR
.SH DESCRIPTION
.\" Add any additional description here
.PP
sg_start sends a START STOP UNIT SCSI command to the given device with
the selected options. The most used options are '--stop' to spin down a disk
and '--start' to spin up a disk. Using 'sg_start --start /dev/sda' on a disk
that is already spinning is harmless. There is also finer grain control
with "power conditions": active, idle and standby. In some contexts
the "stop" state can be considered an additional power condition. 
.PP
Devices that contain removable media such as cd/dvds can use the '--loej'
flag to load the medium when used in conjunction with '--start' (i.e. load
medium then spin up). Alternatively '--loej' may be used to eject the medium
when used alone or when used in conjunction with '--stop' (i.e. spin down
then eject medium). More simply the loading and ejecting of a removable 
medium can be requested with the '--load' and '--eject' options.
.PP
If no option or argument is given then a '--start' is assumed; as the
utility's name suggests.
.TP
0
stop (spin-down) given device.
Active when '--pc=" is not given or '--pc=0'.
.TP
1
start (spin-up) given device.
Active when '--pc=" is not given or '--pc=0'. Harmless if device has
already started (or is in the process of starting).
.TP
--eject
stop the medium and eject it from the drive. Only appropriate for a
device with removable medium. Might be ignored (prevented), see below.
.TP
--fl=<n>
sets the format layer number for the disc to "jump" to (defined in
MMC-5). Values of '<n>' can be 0 to 3. When this option is chosen,
the FL, LoEj and Start bits are set in the cdb as required by MMC-5; thus
the user does not need to set the '--start' and/or '--load' options. 
.TP
-i
sets the IMM bit on the START STOP UNIT command so this utility will
return immediately and not wait for the media to spin down. Same
effect as '--imm=1'. The default action (without this option or
a '--imm=1' option) is to wait until the media spins down before
returning.
.TP
--imm=0|1
when the immediate bit is 1 then this utility returns immediately after
the device has received the command. When this option is 0 (the default)
then the utility returns once the command has completed its action
(i.e. it waits until the device is started or stopped).
.TP
--load
load the medium in the drive and start it. Only appropriate for a
removable medium.
.TP
--loej
load the media when the unit is started or eject it when the unit is
stopped. This option is ignored if 'pc > 0'. Default is off (i.e. don't
attempt to load or eject media). If a start/start indication is not
given (neither "--start" nor "--stop") and this option is given then a
stop and eject action is assumed.
.TP
--pc=<n>
set the 'power conditions' value (in hex); 0 to f (inclusive) are valid.
Default value is 0.
When '--pc=0' then '--eject', '--load', '--loej', '--start' and '--stop'
are active. Some common values are 1 for the active power condition (SBC);
2 for the idle power condition; 3 for the standby power condition; 5 for
sleep power condition (MMC); 7 for LU_CONTROL (SBC), 0xa (decimal 10) for
FORCE_IDLE_0 (SBC) and 0xb (decimal 11) for FORCE_STANDBY_0 (SBC).
See recent SBC-3, MMC-5 and SAS drafts at www.t10.org for more information.
.TP
--start
start (spin-up) given device. Using this option on an already started
device is harmless. Same meaning as "1" argument.
.TP
--stop
stop (spin-down) given device. Same meaning as "0" argument.
.TP
-v
verbose: outputs SCSI command in hex to console before with executing
it. '-vv' and '-vvv' are also accepted yielding greater verbosity.
.TP
-V
print out version string then exit.
.PP
All options, other than '-v' and '-V', can be given with a single "-".
For example: "sg_start -stop /dev/sda" and "sg_start --stop /dev/sda"
are equivalent. The single "-" form is for backward compatibility.
.PP
To avoid confusion, only one of "0", "1", "--load", "--eject", "--start"
and "--stop" can be given.
.PP
If this utility succeeds then its process exits with a status of 0;
otherwise it exits with a non-zero status.
.PP
There is an associated "power condition" mode page (0x1a) in which timer
values can be set for transitioning to either idle or standby state after
a period of inactivity. The sdparm utility can be used to view the
power condition mode page and if required change it.
If a device is in either idle or standby power condition state then
a REQUEST SENSE command (see the sg_requests utility) should yield 
a sense key of "no sense" and an additional sense code of "Low
power condition on" on recent SCSI devices.
.PP
Ejection of removable media (e.g. 'sg_start --eject /dev/hdd' where
the device is an ATAPI cd/dvd drive) may be prevented by a prior
PREVENT ALLOW MEDIUM REMOVAL SCSI command (see sg_prevent). In this
case this utility should fail with an error generated by the device:
illegal request / medium removal prevented. This can be overridden
using sg_prevent or 'sdparm --command=unlock /dev/hdd'.
.PP
In the 2.4 series of Linux kernels the given device must be
a SCSI generic (sg) device. In the 2.6 series block devices (e.g. disks
and SCSI DVDs) can also be specified. For example "sg_start 0 /dev/sda"
will work in the 2.6 series kernels.
.SH NOTES
Earlier versions had a '-s' option to perform a SYNCHRONIZE CACHE command
before the START STOP UNIT command was issued. According to recent SBC-2
drafts this is done implicitly if required. Hence the "-s" option has been
dropped.
.SH AUTHOR
Written by K. Garloff and D. Gilbert
.SH "REPORTING BUGS"
Report bugs to <dgilbert at interlog dot com>.
.SH COPYRIGHT
Copyright \(co 2002-2006 Kurt Garloff, Douglas Gilbert
.br
This software is distributed under the GPL version 2. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
.SH "SEE ALSO"
.B sg_prevent(sg3_utils), sg_requests(sg3_utils), sdparm(sdparm)