man > sg_bg_ctl(8)

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  back‐
       ground  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  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 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 MER‐
       CHANTABILITY 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)