blkdiscard
(8)discard sectors on a device
Options
10-f--forceDisable 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--offsetoffsetByte 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--lengthlengthThe 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--steplengthThe number of bytes to discard within one iteration. The default is to discard all by one ioctl call.
-q--quietSuppress warning messages.
-s--securePerform 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--zerooutZero-fill rather than discard.
-v--verboseDisplay the aligned values of offset and length. If the --step option is specified, it prints the discard progress every second.
-h--helpDisplay help text and exit.
-V--versionDisplay version and exit.
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.
EXIT STATUS
AUTHORS
Lukas Czerner lczerner@redhat.com, Karel Zak kzak@redhat.com
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/.