util-linux (2.39)
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VersionsBLKDISCARD(8) System Administration 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.
-f, --force
Disable all checking. Since v2.36 the block device is open in exclusive mode (O_EXCL) by default to avoid
collision with mounted filesystem or another kernel subsystem. The --force option disables the exclusive
access mode.
-o, --offset offset
Byte offset into the device from which to start discarding. The provided value must 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 must 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.
-q, --quiet
Suppress warning messages.
-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.
-h, --help
Display help text and exit.
-V, --version
Print version and exit.
EXIT STATUS
blkdiscard has the following exit status values:
0
success
1
failure; incorrect invocation, permissions or any other generic error
2
failure; since v2.39, the device does not support discard operation
AUTHORS
[34mLukas Czerner <lczerner@redhat.com>, [34mKarel Zak <kzak@redhat.com>
SEE ALSO
fstrim(8)
REPORTING BUGS
For bug reports, use the issue tracker at [34mhttps://github.com/util-linux/util-linux/issues.
AVAILABILITY
The blkdiscard command is part of the util-linux package which can be downloaded from [34mLinux Kernel Archive
<https://www.kernel.org/pub/linux/utils/util-linux/>.
util-linux 2.39 2023-03-23 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.
-f, --force
Disable all checking. Since v2.36 the block device is open in exclusive mode (O_EXCL) by default to avoid
collision with mounted filesystem or another kernel subsystem. The --force option disables the exclusive
access mode.
-o, --offset offset
Byte offset into the device from which to start discarding. The provided value must 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 must 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.
-q, --quiet
Suppress warning messages.
-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.
-h, --help
Display help text and exit.
-V, --version
Print version and exit.
EXIT STATUS
blkdiscard has the following exit status values:
0
success
1
failure; incorrect invocation, permissions or any other generic error
2
failure; since v2.39, the device does not support discard operation
AUTHORS
[34mLukas Czerner <lczerner@redhat.com>, [34mKarel Zak <kzak@redhat.com>
SEE ALSO
fstrim(8)
REPORTING BUGS
For bug reports, use the issue tracker at [34mhttps://github.com/util-linux/util-linux/issues.
AVAILABILITY
The blkdiscard command is part of the util-linux package which can be downloaded from [34mLinux Kernel Archive
<https://www.kernel.org/pub/linux/utils/util-linux/>.
util-linux 2.39 2023-03-23 BLKDISCARD(8)