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blkdiscard(8) [centos man page]

BLKDISCARD(8)						       System Administration						     BLKDISCARD(8)

blkdiscard - discard sectors on a device SYNOPSIS
blkdiscard [-o offset] [-l length] [-s] [-v] device DESCRIPTION
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! 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. -h, --help Print help and exit. -o, --offset offset Byte offset in the device from which to discard. Provided value will be aligned to the device sector size. Default value is zero. -l, --length length Number of bytes after starting point to discard. 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. Default value extends to the end of the device. -s, --secure Perform secure discard. Secure discard is the same as regular discard except all copies of the discarded blocks possibly created by garbage collection must also be erased. It has to be supported by the device. -v, --verbose Print aligned offset and length arguments. AUTHOR
Lukas Czerner <> SEE ALSO
The blkdiscard command is part of the util-linux package and is available Linux Kernel Archive < linux/>. util-linux October 2012 BLKDISCARD(8)

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BLOCKDEV(8)						       System Administration						       BLOCKDEV(8)

blockdev - call block device ioctls from the command line SYNOPSIS
blockdev [-q] [-v] command [command...] device [device...] blockdev --report [device...] DESCRIPTION
The utility blockdev allows one to call block device ioctls from the command line. OPTIONS
-V Print version and exit. -q Be quiet. -v Be verbose. --report Print a report for the specified device. It is possible to give multiple devices. If none is given, all devices which appear in /proc/partitions are shown. Note that the partition StartSec is in 512-byte sectors. COMMANDS
It is possible to give multiple devices and multiple commands. --flushbufs Flush buffers. --getalignoff Get alignment offset. --getbsz Print blocksize in bytes. --getdiscardzeroes Get discard zeroes support status. --getfra Get filesystem readahead in 512-byte sectors. --getiomin Get minimum I/O size. --getioopt Get optimal I/O size. --getmaxsect Get max sectors per request --getpbsz Get physical block (sector) size. --getra Print readahead (in 512-byte sectors). --getro Get read-only. Print 1 if the device is read-only, 0 otherwise. --getsize64 Print device size in bytes. --getsize Print device size (32-bit!) in sectors. Deprecated in favor of the --getsz option. --getss Print sectorsize in bytes - usually 512. --getsz Get size in 512-byte sectors. --rereadpt Reread partition table --setbsz bytes Set blocksize. --setfra sectors Set filesystem readahead (same like --setra on 2.6 kernels). --setra sectors Set readahead (in 512-byte sectors). --setro Set read-only. --setrw Set read-write. AUTHOR
blockdev was written by Andries E. Brouwer and rewritten by Karel Zak. AVAILABILITY
The blockdev command is part of the util-linux package and is available from util-linux August 2010 BLOCKDEV(8)

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