63 lines
1.9 KiB
Groff
63 lines
1.9 KiB
Groff
.\" -*- nroff -*-
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.TH FALLOCATE 1 "September 2011" "util-linux" "User Commands"
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.SH NAME
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fallocate \- preallocate space to a file
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.SH SYNOPSIS
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.B fallocate
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.RB [ \-n ]
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.RB [ \-p ]
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.RB [ \-o
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.IR offset ]
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.B \-l
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.IR length
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.I filename
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.SH DESCRIPTION
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.B fallocate
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is used to preallocate blocks to a file. For filesystems which support the
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fallocate system call, this is done quickly by allocating blocks and marking
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them as uninitialized, requiring no IO to the data blocks. This is much faster
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than creating a file by filling it with zeros.
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.PP
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As of the Linux Kernel v2.6.31, the fallocate system call is supported by the
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btrfs, ext4, ocfs2, and xfs filesystems.
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.PP
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The exit code returned by
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.B fallocate
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is 0 on success and 1 on failure.
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.PP
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.SH OPTIONS
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The \fIlength\fR and \fIoffset\fR arguments may be followed by the multiplicative
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suffixes KiB=1024, MiB=1024*1024, and so on for GiB, TiB, PiB, EiB, ZiB and YiB
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(the "iB" is 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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.IP "\fB\-n, \-\-keep-size\fP"
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Do not modify the apparent length of the file. This may effectively allocate
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blocks past EOF, which can be removed with a truncate.
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.IP "\fB\-p, \-\-punch-hole\fP"
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Punch holes in the file, the range should not exceed the length of the file.
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.IP "\fB\-o, \-\-offset\fP \fIoffset\fP
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Specifies the beginning offset of the allocation, in bytes.
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.IP "\fB\-l, \-\-length\fP \fIlength\fP
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Specifies the length of the allocation, in bytes.
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.IP "\fB\-h, \-\-help\fP"
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Display help text and exit.
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.IP "\fB-V, \-\-version"
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Display version information and exit.
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.SH AUTHORS
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.UR sandeen@redhat.com
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Eric Sandeen
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.UE
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.br
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.UR kzak@redhat.com
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Karel Zak
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.UE
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.SH SEE ALSO
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.BR fallocate (2),
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.BR posix_fallocate (3),
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.BR truncate (1)
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.SH AVAILABILITY
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The fallocate command is part of the util-linux package and is available from
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.UR ftp://\:ftp.kernel.org\:/pub\:/linux\:/utils\:/util-linux/
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Linux Kernel Archive
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.UE .
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