man > sg_start(8)

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 selected 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": active, idle or standby. This is set with the --pc=PC option.  In  some  contexts
       the "stop" state can be considered an additional power condition.

       Devices  that  contain  removable media such as cd/dvds can use the --loej option 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  re‐
       quested with the --load or --eject' option.

       If no option or argument is given then a --start is assumed; as the utility's name suggests.

       This utility supports two command line syntaxes, the preferred one is shown first in the syn‐
       opsis  and explained in this section. A later section on the old command line syntax outlines
       the second group of options.

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 remov‐
              able medium. Might be ignored (prevented), see below.

       -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 options.

       -i, --immed
              sets  the  IMM  bit on the START STOP UNIT command so this utility will return immedi‐
              ately and not wait for the media to complete the requested 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 media 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  (inclusive)  are  valid
              and  0 is the default. This  'power condition modifier' field in the cdb was added af‐
              ter 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 access 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  com‐
              mand negating the effect of the --stop option.

       -s, --start
              start  (spin-up)  the DEVICE. This sets the START bit in the cdb. Using this option on
              an already started device is harmless. In the absence 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.

       -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 condition mode page and if required change it. If a DE‐
       VICE 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.

       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 SCSI PREVENT ALLOW MEDIUM REMOVAL command (see
       sg_prevent). In this case this utility should fail with an error generated by the device: il‐
       legal request / medium removal prevented. This can be overridden using sg_prevent or, for ex‐
       ample, 'sdparm --command=unlock /dev/hdd'.

       The SCSI TEST UNIT READY command can be used to find out whether a DEVICE is ready to  trans‐
       fer  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 replaced 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 ef‐
       fects (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  interface:  when  neither
       --start  nor  --stop (nor proxies for them) are given, --loej performs an eject operation. In
       the same situation the newer interface 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 implic‐
       itly if required. Hence the '-s' option 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 immedi‐
              ately 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.

       --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).

       --load load the medium in the drive and start it.

       --loej sets the LOEJ bit in the START STOP UNIT cdb. When a "start" operation  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  (inclusive)  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 access 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. De‐
              fault 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 executing  it.  '-vv'  and
              '-vvv' are also accepted yielding greater verbosity.

       -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 op‐
       tion.

AUTHOR
       Written by K. Garloff and D. Gilbert

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

COPYRIGHT
       Copyright © 2002-2020 Kurt Garloff, Douglas Gilbert
       This software is distributed under the GPL version 2. There is NO warranty; not even for MER‐
       CHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

SEE ALSO
       sg_prevent(sg3_utils), sg_requests(sg3_utils), sg_turs(sg3_utils) sdparm(sdparm)

sg3_utils-1.43                             September 2020                                SG_START(8)