.\" -*- nroff -*-
.TH BLKDISCARD 8 "October 2012" "util-linux" "System Administration"
.SH NAME
blkdiscard \- discard sectors on a device
.SH SYNOPSIS
.B blkdiscard
.RB [ \-o
.IR offset ]
.RB [ \-l
.IR length ]
.RB [ \-s ]
.RB [ \-v ]
.I device
.SH DESCRIPTION
.B blkdiscard
is used to discard device sectors. This is useful for solid-state
drivers (SSDs) and thinly-provisioned storage. Unlike
.BR fstrim (8)
this command is used directly on the block device.
.PP
By default,
.B blkdiscard
will discard all blocks on the device. Options may be used to modify
this behavior based on range or size, as explained below.
.PP
The
.I device
argument is the pathname of the block device.
.PP
.B WARNING: All data in the discarded region on the device will be lost!
.SH OPTIONS
The
.I offset
and
.I 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.
.IP "\fB\-h, \-\-help\fP"
Display help text and exit.
.IP "\fB\-o, \-\-offset\fP \fIoffset\fP"
Byte offset in the device from which to discard. Provided value will be
aligned to the device sector size. Default value is zero.
.IP "\fB\-l, \-\-length\fP \fIlength\fP"
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,
.B blkdiscard
will stop at the device size boundary. Default value extends to the end
of the device.
.IP "\fB\-s, \-\-secure\fP"
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.
.IP "\fB\-v, \-\-verbose\fP"
Print aligned
.I offset
and
.I length
arguments.
.SH AUTHOR
.MT lczerner@redhat.com
Lukas Czerner
.ME
.SH SEE ALSO
.BR fstrim (8)
.SH AVAILABILITY
The blkdiscard command is part of the util-linux package and is available
.UR ftp://\:ftp.kernel.org\:/pub\:/linux\:/utils\:/util-linux/
Linux Kernel Archive
.UE .
