blkdiscard

BLKDISCARD(8)                System Administration               BLKDISCARD(8)

NAME
       blkdiscard - discard sectors on a device

SYNOPSIS
       blkdiscard [options] [-o offset] [-l length] device

DESCRIPTION
       blkdiscard is used to discard device sectors. This is useful for
       solid-state drivers (SSDs) and thinly-provisioned storage. Unlike
       fstrim(8), this command is used directly on the block device.

       By default, blkdiscard will discard all blocks on the device. Options
       may be used to modify this behavior based on range or size, as
       explained below.

       The device argument is the pathname of the block device.

       WARNING: All data in the discarded region on the device will be lost!

OPTIONS
       The offset and length arguments may be followed by the multiplicative
       suffixes KiB (=1024), MiB (=1024*1024), and so on for GiB, TiB, PiB,
       EiB, ZiB and YiB (the "iB" is optional, e.g., "K" has the same meaning
       as "KiB") or the suffixes KB (=1000), MB (=1000*1000), and so on for
       GB, TB, PB, EB, ZB and YB.

       -f, --force
           Disable all checking. Since v2.36 the block device is open in
           exclusive mode (O_EXCL) by default to avoid collision with mounted
           filesystem or another kernel subsystem. The --force option disables
           the exclusive access mode.

       -o, --offset offset
           Byte offset into the device from which to start discarding. The
           provided value must be aligned to the device sector size. The
           default value is zero.

       -l, --length length
           The number of bytes to discard (counting from the starting point).
           The provided value must be aligned to the device sector size. If
           the specified value extends past the end of the device, blkdiscard
           will stop at the device size boundary. The default value extends to
           the end of the device.

       -p, --step length
           The number of bytes to discard within one iteration. The default is
           to discard all by one ioctl call.

       -s, --secure
           Perform a secure discard. A secure discard is the same as a regular
           discard except that all copies of the discarded blocks that were
           possibly created by garbage collection must also be erased. This
           requires support from the device.

       -z, --zeroout
           Zero-fill rather than discard.

       -v, --verbose
           Display the aligned values of offset and length. If the --step
           option is specified, it prints the discard progress every second.

       -V, --version
           Display version information and exit.

       -h, --help
           Display help text and exit.

AUTHORS
       Lukas Czerner <lczerner@redhat.com>

SEE ALSO
       fstrim(8)

REPORTING BUGS
       For bug reports, use the issue tracker at
       https://github.com/karelzak/util-linux/issues.

AVAILABILITY
       The blkdiscard command is part of the util-linux package which can be
       downloaded from Linux Kernel Archive
       <https://www.kernel.org/pub/linux/utils/util-linux/>.

util-linux 2.37.2                 2021-06-02                     BLKDISCARD(8)