Manual: 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 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 , Karel Zak 

SEE ALSO
       fstrim(8)

REPORTING BUGS
       For bug reports, use the issue tracker .

AVAILABILITY
       The blkdiscard command is part of the util-linux package which can be downloaded from Linux Kernel Archive
       .

util-linux 2.41.3					 2025-12-15					       BLKDISCARD(8)