blkdiscard(8) [centos man page]

BLKDISCARD(8)						       System Administration						     BLKDISCARD(8)

NAME

       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 <lczerner@redhat.com>

SEE ALSO

       fstrim(8)

AVAILABILITY

       The blkdiscard command is part of the util-linux package and is available Linux Kernel Archive  <ftp://ftp.kernel.org/pub/linux/utils/util-
       linux/>.

util-linux							   October 2012 						     BLKDISCARD(8)

BLOCKDEV(8)						       System Administration						       BLOCKDEV(8)

NAME

       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. Note that the block size is specific to the current file descriptor opening the block device, so the change of  block
	      size only persists for as long as blockdev has the device open, and is lost once blockdev exits.

       --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 ftp://ftp.kernel.org/pub/linux/utils/util-linux/.

util-linux							    August 2010 						       BLOCKDEV(8)