SG_START(8) SG3_UTILS SG_START(8) NAME sg_start - send SCSI START STOP UNIT command: start, stop, load or eject medium SYNOPSIS sg_start [0] [1] [--eject] [--help] [--fl=FL] [--immed] [--load] [--loej] [--mod=PC_MOD] [--noflush] [--pc=PC] [--readonly] [--start] [--stop] [--verbose] [--version] DEVICE sg_start [--eject] [--fl=FL] [-i] [--imm=0|1] [--load] [--loej] [--mod=PC_MOD] [--noflush] [--pc=PC] [-r] [--start] [--stop] [-v] [-V] [0|1] DEVICE DESCRIPTION sg_start sends a SCSI START STOP UNIT command to the DEVICE with the se- lected options. The most used options are --stop to spin down a disk and --start to spin up a disk. Using --start on a disk that is already spinning is harmless. There is also finer grain control with "power condition": ac- tive, idle or standby. This is set with the --pc=PC option. In some con- texts the "stop" state can be considered an additional power condition. Devices that contain removable media such as cd/dvds can use the --loej op- tion 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 in conjunction with --stop (i.e. spin down then eject medium). More simply, the loading or ejecting of a removable medium can be requested with the --load or --eject' option. If no option or argument is given then a --start is assumed; as the util- ity's name suggests. This utility supports two command line syntaxes, the preferred one is shown first in the synopsis and explained in this section. A later section on the old command line syntax outlines the second group of options. Linux note: best not to use a standard block device name (e.g. /dev/sdc) with the --stop option. Use a sg or bsg device node instead (see lsscsi(8) ). The block layer will sometimes notice the disk spinning down and decide: "that's not right" and spin it up again! OPTIONS Arguments to long options are mandatory for short options as well. 0 same action as --stop. 1 same action as --start. -e, --eject stop the medium and eject it from the drive. Only appropriate for a device with removable medium. Might be ignored (prevented), see be- low. Note, this is an operation that can be done on a tape drive or CD/DVD/BD player, not on a hard disk or SSD! -h, --help print out the usage message then exit. -f, --fl=FL sets the format layer number for the disc to "jump" to (defined in MMC-5). Values of FL 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 op- tions. -i, --immed sets the IMM bit on the START STOP UNIT command so this utility will return immediately and not wait for the media to complete the re- quested action. The default is to wait until the media to complete the requested action before returning. -l, --load load the medium in the drive and start it. Only appropriate for a removable medium. -L, --loej sets the LOEJ bit on the START STOP UNIT command. This loads the me- dia when the unit is started or eject it when the unit is stopped (i.e. works in conjunction with START bit in cdb). 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 (i.e. neither --start nor --stop) and this option is given then a load and start action is assumed. -m, --mod=PC_MOD where PC_MOD is the 'power condition modifier' value. 0 to 15 (in- clusive) are valid and 0 is the default. This 'power condition mod- ifier' field in the cdb was added after sbc3r13. -n, --noflush do not perform a flush to media (e.g. like SYNCHRONIZE CACHE does) before a variant of this utility that limits access to the media. Using the --stop option is an example of something that limits ac- cess to the media. This 'noflush' field in the cdb was added after sbc3r13. -O, --old Switch to older style options. Please use as first option. -p, --pc=PC where PC is the 'power conditions' value. 0 to 15 (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. -r, --readonly open the DEVICE in read-only mode. Maybe required in Linux to stop a nuisance spin-up if the DEVICE is an ATA disk. The nuisance spin-up may occur at the end of this command negating the effect of the --stop option. -s, --start start (spin-up) the DEVICE. This sets the START bit in the cdb. Us- ing this option on an already started device is harmless. In the ab- sence of other options, this option defaults (i.e. set the START cdb bit). -S, --stop stop (spin-down) the DEVICE. This clears the START bit in the cdb. This operation is typically done on a hard disk or SSD. In the case of a SSD it will be placed in low power mode and may need a start operation later before normal IO can resume. -v, --verbose increase the level of verbosity. Can be used multiple times. -V, --version print out version string then exit. NOTES To avoid confusion, only one of 0, 1 --eject, --load, --start and --stop should be given. 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 con- dition 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 addi- tional sense code of "Low power condition on" on recent SCSI devices. Ejection of removable media (e.g. 'sg_start --eject /dev/hdd' where the DE- VICE is an ATAPI cd/dvd drive) may be prevented by a prior SCSI PREVENT AL- LOW MEDIUM REMOVAL 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, for example, 'sdparm --command=unlock /dev/hdd'. The SCSI TEST UNIT READY command can be used to find out whether a DEVICE is ready to transfer data. If rotating media is stopped or still coming up to speed, then the TEST UNIT READY command will yield a "not ready" sense key and an more informative additional sense code. See the sg_turs utility. 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. SCSI disks and DVD drives) can also be specified. For example "sg_start 0 /dev/sda" will work in the 2.6 series kernels. In the Linux 2.6 series, especially with ATA disks, using this utility to stop (spin down) a disk may not be sufficient and other mechanisms will start the disk again some time later. The user might additionally mark the disk as "offline" with 'echo offline > /sys/block/sda/device/state' where sda is the block name of the disk. To restart the disk "offline" can be re- placed with "running". Note that once the 'state' is set to offline, no SCSI commands can be sent to the device until it is set back to running. Also stopping a disk via a pass-through interface (e.g. /dev/sg1 or /dev/bsg/1:0:0:0) may reduce unwanted side effects (such as restarting it again when this utility completes). EXIT STATUS The exit status of sg_start is 0 when it is successful. Otherwise see the sg3_utils(8) man page. OLDER COMMAND LINE OPTIONS The options in this section were the only ones available prior to sg3_utils version 1.23 . Since then this utility defaults to the newer command line options which can be overridden by using --old (or -O) as the first option. See the ENVIRONMENT VARIABLES section for another way to force the use of these older command line options. Note that the action of --loej is slightly different in the older inter- face: when neither --start nor --stop (nor proxies for them) are given, --loej performs an eject operation. In the same situation the newer inter- face will perform a load operation. Earlier versions of sg_start 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' op- tion has been dropped. 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. 0 stop (spin-down) DEVICE. 1 start (spin-up) DEVICE. --eject stop the medium and eject it from the drive. --fl=FL sets the format layer number for the disc to "jump" to (defined in MMC-5). -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 ef- fect as '--imm=1'. The default action (without this option or a '--imm=1' option) is to wait until the media spins down before re- turning. --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 com- pleted its action (i.e. it waits until the device is started or stopped). --load load the medium in the drive and start it. --loej sets the LOEJ bit in the START STOP UNIT cdb. When a "start" opera- tion is indicated, then a load and start is performed. When a "stop" operation is indicated, then a stop and eject is performed. When neither a "start" or "stop" operation is indicated does a stop and eject. [Note that the last action differs from the new interface in which the option of this name defaults to load and start.] -N, --new Switch to the newer style options. --mod=PC_MOD where PC_MOD is the 'power condition modifier' value. 0 to 15 (in- clusive) are valid and 0 is the default. This field was added after sbc3r13. --noflush do not perform a flush to media (e.g. like SYNCHRONIZE CACHE does) before a variant of this utility that limits access to the media. Using the --stop option is an example of something that limits ac- cess to the media. This field was added after sbc3r13. --pc=PC where PC is the 'power condition' value (in hex). 0 to f (inclusive) are valid. Default value is 0. -r see the --readonly option above. May be useful for ATA disks. --start start (spin-up) DEVICE. --stop stop (spin-down) DEVICE. Same meaning as "0" argument. -v verbose: outputs SCSI command in hex to console before with execut- ing it. '-vv' and '-vvv' are also accepted yielding greater ver- bosity. -V print out version string then exit. ENVIRONMENT VARIABLES Since sg3_utils version 1.23 the environment variable SG3_UTILS_OLD_OPTS can be given. When it is present this utility will expect the older command line options. So the presence of this environment variable is equivalent to using --old (or -O) as the first command line option. AUTHOR Written by K. Garloff and D. Gilbert REPORTING BUGS Report bugs to <dgilbert at interlog dot com>. COPYRIGHT Copyright (C) 2002-2021 Kurt Garloff, Douglas Gilbert This software is distributed under the GPL version 2. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. SEE ALSO sg_prevent(sg3_utils), sg_requests(sg3_utils), sg_turs(sg3_utils) sd- parm(sdparm), lsscsi(lsscsi) sg3_utils-1.47 April 2021 SG_START(8)
NAME | SYNOPSIS | DESCRIPTION | OPTIONS | NOTES | EXIT STATUS | OLDER COMMAND LINE OPTIONS | ENVIRONMENT VARIABLES | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO
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