NAME

       blkdiscard - discard sectors on a device

SYNOPSIS

       blkdiscard [options] [-o offset] [-l length] 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.

       -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 collection 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 specified, it prints the
              discard progress every second.

       -V, --version
              Display version information and exit.

       -h, --help
              Display help text and exit.

AUTHOR

       Lukas Czerner

SEE ALSO

       fstrim(8)

AVAILABILITY

       The blkdiscard command is part of the util-linux package and is available Linux Kernel Archive.

util-linux                                          July 2014                                      BLKDISCARD(8)