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| − | =btrfs-subvolume(8) Manual Page=
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| − | ==NAME==
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| − | btrfs-subvolume - control btrfs subvolume(s)
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| − | ==SYNOPSIS==
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| − | '''btrfs subvolume''' <subcommand> [<args>]
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| − | ==DESCRIPTION==
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| − | '''btrfs subvolume''' is used to control the filesystem to create/delete/list/show subvolumes and snapshots.
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| − | ==SUBVOLUME AND SNAPSHOT==
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| − | A subvolume in btrfs is not like an LVM logical volume, which is quite independent from each other, a btrfs subvolume has its hierarchy and relations between other subvolumes.
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| − | A subvolume in btrfs can be accessed in two ways.
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| − | # From the parent subvolume<br /> When accessing from the parent subvolume, the subvolume can be used just like a directory. It can have child subvolumes and its own files/directories.
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| − | # Separate mounted filesystem<br /> When [http://man7.org/linux/man-pages/man8/mount.8.html mount(8)] using '''subvol''' or '''subvolid''' mount option, one can access files/directories/subvolumes inside it, but nothing in parent subvolumes.
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| − | Also every btrfs filesystem has a default subvolume as its initially top-level subvolume, whose subvolume id is 5(FS_TREE).
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| − | A btrfs snapshot is much like a subvolume, but shares its data(and metadata) with other subvolume/snapshot. Due to the capabilities of COW, modifications inside a snapshot will only show in a snapshot but not in its source subvolume.
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| − | Although in btrfs, subvolumes/snapshots are treated as directories, only subvolume/snapshot can be the source of a snapshot, snapshot can not be made from normal directories.
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| − | ==SUBCOMMAND==
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| − | ; '''create''' [-i <qgroupid>] [<dest>]<name>
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| − | : Create a subvolume <name> in <dest>. <br /> If <dest> is not given, subvolume <name> will be created in the currently directory. <br /><code>Options</code><br />
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| − | :; -i <qgroupid>
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| − | :: Add the newly created subvolume to a qgroup. This option can be given multiple times.
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| − | ; '''delete''' [options] <subvolume> [<subvolume>…]
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| − | : Delete the subvolume(s) from the filesystem. <br /> If <subvolume> is not a subvolume, btrfs returns an error but continues if there are more arguments to process. <br /> The corresponding directory is removed instantly but the data blocks are removed later. The deletion does not involve full commit by default due to performance reasons (as a consequence, the subvolume may appear again after a crash). Use one of the '''--commit''' options to wait until the operation is safely stored on the media. <br /><code>Options</code><br />
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| − | :; -c|--commit-after
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| − | :: wait for transaction commit at the end of the operation <br />
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| − | :; -C|--commit-each
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| − | :: wait for transaction commit after delet each subvolume
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| − | ; '''list''' [options] [-G [+|-]<value>] [-C [+|-]<value>] [--sort=rootid,gen,ogen,path] <path>
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| − | : List the subvolumes present in the filesystem <path>. <br /> For every subvolume the following information is shown by default.<br /> ID <ID> top level <ID> path <path><br /> where path is the relative path of the subvolume to the top level subvolume. The subvolume’s ID may be used by the subvolume set-default command, or at mount time via the subvolid= option. If <code>-p</code> is given, then parent <ID> is added to the output between ID and top level. The parent’s ID may be used at mount time via the <code>subvolrootid=</code> option. <br /><code>Options</code><br />
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| − | :; -p
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| − | :: print parent ID.
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| − | :; -a
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| − | :: print all the subvolumes in the filesystem and distinguish between absolute and relative path with respect to the given <path>.
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| − | :; -c
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| − | :: print the ogeneration of the subvolume, aliases: ogen or origin generation.
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| − | :; -g
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| − | :: print the generation of the subvolume.
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| − | :; -o
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| − | :: print only subvolumes bellow specified <path>.
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| − | :; -u
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| − | :: print the UUID of the subvolume.
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| − | :; -q
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| − | :: print the parent uuid of subvolumes (and snapshots).
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| − | :; -t
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| − | :: print the result as a table.
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| − | :; -s
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| − | :: only snapshot subvolumes in the filesystem will be listed.
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| − | :; -r
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| − | :: only readonly subvolumes in the filesystem will be listed.
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| − | :; -G [+|-]<value>
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| − | :: list subvolumes in the filesystem that its generation is >=, <= or = value. '+' means >= value, '-' means <= value, If there is neither '+' nor '-', it means = value.
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| − | :; -C [+|-]<value>
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| − | :: list subvolumes in the filesystem that its ogeneration is >=, <= or = value. The usage is the same to '''-g''' option.
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| − | :; --sort=rootid,gen,ogen,path
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| − | :: list subvolumes in order by specified items. you can add '+' or '-' in front of each items, '+' means ascending, '-' means descending. The default is ascending. <br /> for --sort you can combine some items together by ',', just like -sort=+ogen,-gen,path,rootid.
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| − | ; '''snapshot''' [-r] <source> <dest>|[<dest>/]<name>
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| − | : Create a writable/readonly snapshot of the subvolume <source> with the name <name> in the <dest> directory. <br /> If only <dest> is given, the subvolume will be named the basename of <source>. If <source> is not a subvolume, btrfs returns an error. If '''-r''' is given, the snapshot will be readonly.
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| − | ; '''get-default''' <path>
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| − | : Get the default subvolume of the filesystem <path>. <br /> The output format is similar to '''subvolume list''' command.
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| − | ; '''set-default''' <id> <path>
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| − | : Set the subvolume of the filesystem <path> which is mounted as default. <br /> The subvolume is identified by <id>, which is returned by the '''subvolume list''' command.
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| − | ; '''find-new''' <subvolume> <last_gen>
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| − | : List the recently modified files in a subvolume, after <last_gen> ID.
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| − | ; '''show''' <path>
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| − | : Show information of a given subvolume in the <path>.
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| − | ==EXIT STATUS== | + | |
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| − | '''btrfs subvolume''' returns a zero exit status if it succeeds. Non zero is returned in case of failure.
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| − | ==AVAILABILITY==
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| − | '''btrfs''' is part of btrfs-progs. Please refer to the btrfs wiki http://btrfs.wiki.kernel.org for further details.
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| − | ==SEE ALSO==
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| − | [[Manpage/mkfs.btrfs|mkfs.btrfs(8)]], [[Manpage/btrfs-subvolume|btrfs-subvolume(8)]], [[Manpage/btrfs-quota|btrfs-quota(8)]], [[Manpage/btrfs-qgroup|btrfs-qgroup(8)]],
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| − | [[Category:Manpage]]
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