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blkdiscard(8)


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 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/.



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