centos man page for blkdiscard

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)