blkdiscard - discard sectors on a device
blkdiscard [options] [-o offset] [-l
length] device
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!
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.