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 performed.

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  operations;
              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.

NOTES

       According  to  T10, support for 'background control operations' is indicated 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 Background 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 operations (e.g., garbage collection), which may
       impact response time for normal read requests or write requests from the application client."

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 © 2016 Douglas Gilbert
       This software is distributed under a FreeBSD license. There is NO warranty; not even for  MERCHANTABILITY
       or FITNESS FOR A PARTICULAR PURPOSE.

SEE ALSO

       sg_vpd,sg_logs(sg3_utils); sdparm(sdparm)

sg3_utils-1.43                                      May 2016                                        SG_BG_CTL(8)