335 lines
11 KiB
Groff
335 lines
11 KiB
Groff
.TH BTRFS 8 "" "btrfs" "btrfs"
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.\"
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.\" Man page written by Goffredo Baroncelli <kreijack@inwind.it> (Feb 2010)
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.\"
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.SH NAME
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btrfs \- control a btrfs filesystem
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.SH SYNOPSIS
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\fBbtrfs\fP \fBsubvolume snapshot\fP\fI [-r] <source> [<dest>/]<name>\fP
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.PP
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\fBbtrfs\fP \fBsubvolume delete\fP\fI <subvolume>\fP
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.PP
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\fBbtrfs\fP \fBsubvolume create\fP\fI [<dest>/]<name>\fP
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.PP
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\fBbtrfs\fP \fBsubvolume list\fP\fI [-p] <path>\fP
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.PP
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\fBbtrfs\fP \fBsubvolume set-default\fP\fI <id> <path>\fP
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.PP
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\fBbtrfs\fP \fBsubvolume get-default\fP\fI <path>\fP
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.PP
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\fBbtrfs\fP \fBfilesystem defragment\fP -c[zlib|lzo] [-l \fIlen\fR] \
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[-s \fIstart\fR] [-t \fIsize\fR] -[vf] <\fIfile\fR>|<\fIdir\fR> \
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[<\fIfile\fR>|<\fIdir\fR>...]
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.PP
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\fBbtrfs\fP \fBfilesystem sync\fP\fI <path> \fP
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.PP
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\fBbtrfs\fP \fBfilesystem resize\fP\fI [devid:][+/\-]<size>[gkm]|[devid:]max <filesystem>\fP
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.PP
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\fBbtrfs\fP \fBfilesystem label\fP\fI <dev> [newlabel]\fP
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.PP
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\fBbtrfs\fP \fBsubvolume find-new\fP\fI <subvolume> <last_gen>\fP
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.PP
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\fBbtrfs\fP \fBfilesystem balance\fP\fI <path> \fP
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.PP
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\fBbtrfs\fP \fBdevice scan\fP\fI [--all-devices|<device> [<device>...]]\fP
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.PP
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\fBbtrfs\fP \fBdevice show\fP\fI [--all-devices|<uuid>|<label>]\fP
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.PP
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\fBbtrfs\fP \fBdevice add\fP\fI <device> [<device>...] <path> \fP
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.PP
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\fBbtrfs\fP \fBdevice delete\fP\fI <device> [<device>...] <path> \fP
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.PP
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\fBbtrfs\fP \fBscrub start\fP [-Bdqru] {\fI<path>\fP|\fI<device>\fP}
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.PP
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\fBbtrfs\fP \fBscrub cancel\fP {\fI<path>\fP|\fI<device>\fP}
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.PP
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\fBbtrfs\fP \fBscrub resume\fP [-Bdqru] {\fI<path>\fP|\fI<device>\fP}
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.PP
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\fBbtrfs\fP \fBscrub status\fP [-d] {\fI<path>\fP|\fI<device>\fP}
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.PP
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\fBbtrfs\fP \fBinspect-internal inode-resolve\fP [-v] \fI<inode>\fP \fI<path>\fP
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.PP
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\fBbtrfs\fP \fBinspect-internal logical-resolve\fP
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[-Pv] \fI<logical>\fP \fI<path>\fP
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.PP
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\fBbtrfs\fP \fBhelp|\-\-help|\-h \fP\fI\fP
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.PP
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\fBbtrfs\fP \fB<command> \-\-help \fP\fI\fP
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.PP
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.SH DESCRIPTION
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.B btrfs
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is used to control the filesystem and the files and directories stored. It is
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the tool to create or destroy a snapshot or a subvolume for the
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filesystem, to defrag a file or a directory, flush the data to the disk,
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to resize the filesystem, to scan the device.
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It is possible to abbreviate the commands unless the commands are ambiguous.
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For example: it is possible to run
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.I btrfs sub snaps
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instead of
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.I btrfs subvolume snapshot.
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But
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.I btrfs file s
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is not allowed, because
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.I file s
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may be interpreted both as
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.I filesystem show
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and as
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.I filesystem sync.
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In this case
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.I btrfs
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returns filesystem sync
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If a command is terminated by
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.I --help
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, the detailed help is showed. If the passed command matches more commands,
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detailed help of all the matched commands is showed. For example
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.I btrfs dev --help
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shows the help of all
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.I device*
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commands.
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.SH COMMANDS
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.TP
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\fBsubvolume snapshot\fR\fI [-r] <source> [<dest>/]<name>\fR
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Create a writable/readonly snapshot of the subvolume \fI<source>\fR with the
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name \fI<name>\fR in the \fI<dest>\fR directory. If \fI<source>\fR is not a
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subvolume, \fBbtrfs\fR returns an error. If \fI-r\fR is given, the snapshot
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will be readonly.
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.TP
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\fBsubvolume delete\fR\fI <subvolume>\fR
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Delete the subvolume \fI<subvolume>\fR. If \fI<subvolume>\fR is not a
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subvolume, \fBbtrfs\fR returns an error.
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.TP
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\fBsubvolume create\fR\fI [<dest>/]<name>\fR
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Create a subvolume in \fI<dest>\fR (or in the current directory if
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\fI<dest>\fR is omitted).
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.TP
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\fBsubvolume list\fR\fI [-p] <path>\fR
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List the subvolumes present in the filesystem \fI<path>\fR. For every
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subvolume the following information is shown by default.
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ID <ID> top level <ID> path <path>
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where path is the relative path of the subvolume to the \fItop level\fR
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subvolume.
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The subvolume's ID may be used by the \fBsubvolume set-default\fR command, or
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at mount time via the \fIsubvol=\fR option.
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If \fI-p\fR is given, then \fIparent <ID>\fR is added to the output between ID
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and top level. The parent's ID may be used at mount time via the
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\fIsubvolrootid=\fR option.
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.TP
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\fBsubvolume set-default\fR\fI <id> <path>\fR
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Set the subvolume of the filesystem \fI<path>\fR which is mounted as
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\fIdefault\fR. The subvolume is identified by \fI<id>\fR, which
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is returned by the \fBsubvolume list\fR command.
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.TP
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\fBsubvolume get-default\fR\fI <path>\fR
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Get the default subvolume of the filesystem \fI<path>\fR. The output format
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is similar to \fBsubvolume list\fR command.
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.TP
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\fBfilesystem defragment\fP -c[zlib|lzo] [-l \fIlen\fR] [-s \fIstart\fR] \
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[-t \fIsize\fR] -[vf] <\fIfile\fR>|<\fIdir\fR> [<\fIfile\fR>|<\fIdir\fR>...]
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Defragment file data and/or directory metadata. To defragment all files in a
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directory you have to specify each one on its own or use your shell wildcards.
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The start position and the number of bytes to defragment can be specified by
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\fIstart\fR and \fIlen\fR. Any extent bigger than threshold will be
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considered already defragged. Use 0 to take the kernel default, and use 1 to
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say every single extent must be rewritten. You can also turn on compression in
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defragment operations.
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\fB-v\fP be verbose
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\fB-c\fP compress file contents while defragmenting
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\fB-f\fP flush filesystem after defragmenting
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\fB-s start\fP defragment only from byte \fIstart\fR onward
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\fB-l len\fP defragment only up to \fIlen\fR bytes
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\fB-t size\fP defragment only files at least \fIsize\fR bytes big
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NOTE: defragmenting with kernels up to 2.6.37 will unlink COW-ed copies of data,
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don't use it if you use snapshots, have de-duplicated your data or made
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copies with \fBcp --reflink\fP.
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.TP
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\fBsubvolume find-new\fR\fI <subvolume> <last_gen>\fR
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List the recently modified files in a subvolume, after \fI<last_gen>\fR ID.
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.TP
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\fBfilesystem sync\fR\fI <path> \fR
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Force a sync for the filesystem identified by \fI<path>\fR.
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.TP
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.\"
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.\" Some wording are extracted by the resize2fs man page
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.\"
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\fBfilesystem resize\fR\fI [devid:][+/\-]<size>[gkm]|[devid:]max <path>\fR
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Resize a filesystem identified by \fI<path>\fR for the underlying device
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\fIdevid\fR. The \fIdevid\fR can be found with \fBbtrfs filesystem show\fR and
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defaults to 1 if not specified.
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The \fI<size>\fR parameter specifies the new size of the filesystem.
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If the prefix \fI+\fR or \fI\-\fR is present the size is increased or decreased
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by the quantity \fI<size>\fR.
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If no units are specified, the unit of the \fI<size>\fR parameter defaults to
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bytes. Optionally, the size parameter may be suffixed by one of the following
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units designators: 'K', 'M', or 'G', kilobytes, megabytes, or gigabytes,
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respectively.
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If 'max' is passed, the filesystem will occupy all available space on the
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device \fIdevid\fR.
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The \fBresize\fR command \fBdoes not\fR manipulate the size of underlying
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partition. If you wish to enlarge/reduce a filesystem, you must make sure you
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can expand the partition before enlarging the filesystem and shrink the
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partition after reducing the size of the filesystem. This can done using
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\fBfdisk(8)\fR or \fBparted(8)\fR to delete the existing partition and recreate
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it with the new desired size. When recreating the partition make sure to use
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the same starting disk cylinder as before.
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.TP
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\fBfilesystem label\fP\fI <dev> [newlabel]\fP
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Show or update the label of a filesystem. \fI<dev>\fR is used to identify the
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filesystem.
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If a \fInewlabel\fR optional argument is passed, the label is changed. The
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following constraints exist for a label:
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.IP
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- the maximum allowable length shall be less or equal than 256 chars
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.IP
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- the label shall not contain the '/' or '\\' characters.
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NOTE: Currently there are the following limitations:
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.IP
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- the filesystem has to be unmounted
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.IP
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- the filesystem should not have more than one device.
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.TP
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\fBfilesystem show\fR [--all-devices|<uuid>|<label>]\fR
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Show the btrfs filesystem with some additional info. If no \fIUUID\fP or
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\fIlabel\fP is passed, \fBbtrfs\fR show info of all the btrfs filesystem.
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If \fB--all-devices\fP is passed, all the devices under /dev are scanned;
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otherwise the devices list is extracted from the /proc/partitions file.
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.TP
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\fBfilesystem balance\fR \fI<path>\fR
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Balance the chunks of the filesystem identified by \fI<path>\fR
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across the devices.
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.TP
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\fBdevice add\fR\fI <dev> [<dev>..] <path>\fR
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Add device(s) to the filesystem identified by \fI<path>\fR.
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.TP
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\fBdevice delete\fR\fI <dev> [<dev>..] <path>\fR
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Remove device(s) from a filesystem identified by \fI<path>\fR.
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.TP
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\fBdevice scan\fR \fI[--all-devices|<device> [<device>...]\fR
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If one or more devices are passed, these are scanned for a btrfs filesystem.
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If no devices are passed, \fBbtrfs\fR scans all the block devices listed
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in the /proc/partitions file.
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Finally, if \fB--all-devices\fP is passed, all the devices under /dev are
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scanned.
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.TP
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\fBscrub start\fP [-Bdqru] {\fI<path>\fP|\fI<device>\fP}
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Start a scrub on all devices of the filesystem identified by \fI<path>\fR or on
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a single \fI<device>\fR. Without options, scrub is started as a background
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process. Progress can be obtained with the \fBscrub status\fR command. Scrubbing
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involves reading all data from all disks and verifying checksums. Errors are
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corrected along the way if possible.
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.RS
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\fIOptions\fR
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.IP -B 5
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Do not background and print scrub statistics when finished.
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.IP -d 5
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Print separate statistics for each device of the filesystem (-B only).
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.IP -q 5
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Quiet. Omit error messages and statistics.
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.IP -r 5
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Read only mode. Do not attempt to correct anything.
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.IP -u 5
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Scrub unused space as well. (NOT IMPLEMENTED)
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.RE
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.TP
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\fBscrub cancel\fP {\fI<path>\fP|\fI<device>\fP}
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If a scrub is running on the filesystem identified by \fI<path>\fR, cancel it.
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Progress is saved in the scrub progress file and scrubbing can be resumed later
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using the \fBscrub resume\fR command.
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If a \fI<device>\fR is given, the corresponding filesystem is found and
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\fBscrub cancel\fP behaves as if it was called on that filesystem.
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.TP
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\fBscrub resume\fP [-Bdqru] {\fI<path>\fP|\fI<device>\fP}
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Resume a canceled or interrupted scrub cycle on the filesystem identified by
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\fI<path>\fR or on a given \fI<device>\fR. Does not start a new scrub if the
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last scrub finished successfully.
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.RS
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\fIOptions\fR
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.TP
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see \fBscrub start\fP.
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.RE
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.TP
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\fBscrub status\fP [-d] {\fI<path>\fP|\fI<device>\fP}
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Show status of a running scrub for the filesystem identified by \fI<path>\fR or
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for the specified \fI<device>\fR.
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If no scrub is running, show statistics of the last finished or canceled scrub
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for that filesystem or device.
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.RS
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\fIOptions\fR
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.IP -d 5
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Print separate statistics for each device of the filesystem.
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.RE
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.TP
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\fBinspect-internal inode-resolve\fP [-v] \fI<inode>\fP \fI<path>\fP
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Resolves an <inode> in subvolume <path> to all filesystem paths.
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.RS
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\fIOptions\fR
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.IP -v 5
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verbose mode. print count of returned paths and ioctl() return value
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.RE
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.TP
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\fBinspect-internal logical-resolve\fP [-Pv] \fI<logical>\fP \fI<path>\fP
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Resolves a <logical> address in the filesystem mounted at <path> to all inodes.
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By default, each inode is then resolved to a file system path (similar to the
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\fBinode-resolve\fP subcommand).
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.RS
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\fIOptions\fR
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.IP -P 5
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skip the path resolving and print the inodes instead
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.IP -v 5
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verbose mode. print count of returned paths and all ioctl() return values
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.RE
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.SH EXIT STATUS
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\fBbtrfs\fR returns a zero exist status if it succeeds. Non zero is returned in
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case of failure.
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.SH AVAILABILITY
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.B btrfs
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is part of btrfs-progs. Btrfs filesystem is currently under heavy development,
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and not suitable for any uses other than benchmarking and review.
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Please refer to the btrfs wiki http://btrfs.wiki.kernel.org for
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further details.
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.SH SEE ALSO
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.BR mkfs.btrfs (8)
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