BLKDISCARD(8) - Linux man page online | Administration and privileged commands
Discard sectors on a device.
BLKDISCARD(8) System Administration BLKDISCARD(8)
util-linux July 2014 BLKDISCARD(8)
NAMEblkdiscard - discard sectors on a device
SYNOPSISblkdiscard [options] [-o offset] [-l length] device
DESCRIPTIONblkdiscard 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 mod‐ ify 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!
OPTIONSThe 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. -o, --offset offset Byte offset into the device from which to start discarding. The provided value will 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 will 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 col‐ lection 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 speci‐ fied, it prints the discard progress every second. -V, --version Display version information and exit. -h, --help Display help text and exit.
AUTHORLukas Czerner ⟨@redhat.com⟩
AVAILABILITYThe blkdiscard command is part of the util-linux package and is available Linux Kernel Archive ⟨https://www.kernel.org/pub/linux/utils/util-linux/⟩.
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