86 lines
2.5 KiB
Groff
86 lines
2.5 KiB
Groff
.TH BLKDISCARD 8 "July 2014" "util-linux" "System Administration"
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.SH NAME
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blkdiscard \- discard sectors on a device
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.SH SYNOPSIS
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.B blkdiscard
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[options]
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.RB [ \-o
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.IR offset ]
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.RB [ \-l
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.IR length ]
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.I device
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.SH DESCRIPTION
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.B blkdiscard
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is used to discard device sectors. This is useful for solid-state
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drivers (SSDs) and thinly-provisioned storage. Unlike
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.BR fstrim (8),
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this command is used directly on the block device.
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.PP
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By default,
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.B blkdiscard
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will discard all blocks on the device. Options may be used to modify
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this behavior based on range or size, as explained below.
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.PP
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The
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.I device
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argument is the pathname of the block device.
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.PP
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.B WARNING: All data in the discarded region on the device will be lost!
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.SH OPTIONS
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The
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.I offset
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and
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.I length
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arguments may be followed by the multiplicative suffixes KiB (=1024),
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MiB (=1024*1024), and so on for GiB, TiB, PiB, EiB, ZiB and YiB (the "iB" is
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optional, e.g., "K" has the same meaning as "KiB") or the suffixes
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KB (=1000), MB (=1000*1000), and so on for GB, TB, PB, EB, ZB and YB.
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.TP
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.BR \-o , " \-\-offset \fIoffset"
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Byte offset into the device from which to start discarding. The provided value
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will be aligned to the device sector size. The default value is zero.
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.TP
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.BR \-l , " \-\-length \fIlength"
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The number of bytes to discard (counting from the starting point). The provided value
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will be aligned to the device sector size. If the specified value extends past
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the end of the device,
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.B blkdiscard
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will stop at the device size boundary. The default value extends to the end
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of the device.
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.TP
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.BR \-p , " \-\-step \fIlength"
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The number of bytes to discard within one iteration. The default is to discard
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all by one ioctl call.
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.TP
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.BR \-s , " \-\-secure"
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Perform a secure discard. A secure discard is the same as a regular discard
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except that all copies of the discarded blocks that were possibly created by
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garbage collection must also be erased. This requires support from the device.
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.TP
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.BR \-z , " \-\-zeroout"
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Zero-fill rather than discard.
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.TP
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.BR \-v , " \-\-verbose"
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Display the aligned values of
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.I offset
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and
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.IR length .
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If the \fB\-\-step\fR option is specified, it prints the discard progress every second.
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.TP
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.BR \-V , " \-\-version"
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Display version information and exit.
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.TP
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.BR \-h , " \-\-help"
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Display help text and exit.
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.SH AUTHOR
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.MT lczerner@redhat.com
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Lukas Czerner
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.ME
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.SH SEE ALSO
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.BR fstrim (8)
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.SH AVAILABILITY
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The blkdiscard command is part of the util-linux package and is available
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.UR https://\:www.kernel.org\:/pub\:/linux\:/utils\:/util-linux/
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Linux Kernel Archive
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.UE .
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