NAME¶btrfs-subvolume - manage btrfs subvolumes
SYNOPSIS¶btrfs subvolume <subcommand> [<args>]
DESCRIPTION¶btrfs subvolume is used to create/delete/list/show btrfs subvolumes and snapshots.
SUBVOLUME AND SNAPSHOT¶A subvolume is a part of filesystem with it’s own and independent file/directory hierarchy. Subvolumes can share file extents. A snapshot is also subvolume, but with a given initial content of the original subvolume.
A subvolume in btrfs is not like an LVM logical volume, which is block-level snapshot while btrfs subvolumes are file extent-based.
A subvolume looks like a normal directory, with some additional operations described below. Subvolumes can be renamed or moved, nesting subvolumes is not restricted but has some implications regarding snapshotting.
A subvolume in btrfs can be accessed in two ways:
In the latter case the parent directory is not visible and accessible. This is similar to a bind mount, and in fact the subvolume mount does exactly that.
A freshly created filesystem is also a subvolume, called top-level, internally has an id 5. This subvolume cannot be removed or replaced by another subvolume. This is also the subvolume that will be mounted by default, unless the default subvolume has been changed (see subcommand set-default).
A snapshot is a subvolume like any other, with given initial content. By default, snapshots are created read-write. File modifications in a snapshot do not affect the files in the original subvolume.
SUBCOMMAND¶create [-i <qgroupid>] [<dest>/]<name>
If <dest> is not given, subvolume <name> will be created in the current directory.
delete [options] <subvolume> [<subvolume>...]
If <subvolume> is not a subvolume, btrfs returns an error but continues if there are more arguments to process.
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.
find-new <subvolume> <last_gen>
The output format is similar to subvolume list command.
list [options] [-G [+|-]<value>] [-C [+|-]<value>] [--sort=rootid,gen,ogen,path] <path>
For every subvolume the following information is shown by default.
ID <ID> top level <ID> path <path> 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 -p 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 subvolrootid= option.
for --sort you can combine some items together by ',', just like --sort=+ogen,-gen,path,rootid.
set-default <id> <path>
The subvolume is identified by <id>, which is returned by the subvolume list command.
snapshot [-r] <source> <dest>|[<dest>/]<name>
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.
sync <path> [subvolid...]
EXIT STATUS¶btrfs subvolume returns a zero exit status if it succeeds. A non-zero value is returned in case of failure.
AVAILABILITY¶btrfs is part of btrfs-progs. Please refer to the btrfs wiki http://btrfs.wiki.kernel.org for further details.
SEE ALSO¶mkfs.btrfs(8), mount(8), btrfs-quota(8), btrfs-qgroup(8),