blkdiscard - discard sectors on a device
blkdiscard [options] [-o offset] [-l length]
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
WARNING: All data in the discarded region on the device will be
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.
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
-p, --step length
The number of bytes to discard within one iteration. The
default is to discard all by one ioctl call.
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.
Zero-fill rather than discard.
Display the aligned values of offset and
length. If the --step option is specified, it prints the discard
progress every second.
Display version information and exit.
Display help text and exit.
Lukas Czerner <email@example.com>