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 drives (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!

       Since util-linux v2.41, fdisk has the ability to discard sectors on
       both partitions and unpartitioned areas using the 'T' command.
       Additionally, sfdisk has the option --discard-free to discard
       unpartitioned areas.

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.

       -q, --quiet
	   Suppress warning messages.

       -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.

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

       -V, --version
	   Display version and exit.

EXIT STATUS
       blkdiscard has the following exit status values:

       0
	   success

       1
	   failure; incorrect invocation, permissions or any other generic
	   error

       2
	   failure; since v2.39, the device does not support discard operation

AUTHORS
       Lukas Czerner <lczerner@redhat.com>, Karel Zak <kzak@redhat.com>

SEE ALSO
       fstrim(8)

REPORTING BUGS
       For bug reports, use the issue tracker
       <https://github.com/util-linux/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 2.41.2		  2025-09-22			 BLKDISCARD(8)