BTRFS-SUBVOLUME(8) Btrfs Manual BTRFS-SUBVOLUME(8)NAMEbtrfs-subvolume - control btrfs subvolume(s)SYNOPSIS
btrfs subvolume <subcommand> [<args>]
DESCRIPTION
btrfs subvolume is used to control the filesystem to
create/delete/list/show subvolumes and snapshots.
SUBVOLUME AND SNAPSHOT
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.
A subvolume in btrfs can be accessed in two ways.
1. From the parent subvolume
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.
2. Separate mounted filesystem
When mount(8) using subvol or subvolid mount option, one can access
files/directories/subvolumes inside it, but nothing in parent
subvolumes.
Also every btrfs filesystem has a default subvolume as its initially
top-level subvolume, whose subvolume id is 5(FS_TREE).
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.
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.
SUBCOMMAND
create [-i <qgroupid>] [<dest>]<name>
Create a subvolume <name> in <dest>.
If <dest> is not given, subvolume <name> will be created in the
currently directory.
Options
-i <qgroupid>
Add the newly created subvolume to a qgroup. This option can be
given multiple times.
delete [options] <subvolume> [<subvolume>...]
Delete the subvolume(s) from the filesystem.
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.
Options
-c|--commit-after
wait for transaction commit at the end of the operation
-C|--commit-each
wait for transaction commit after delet each subvolume
list [options] [-G [+|-]<value>] [-C [+|-]<value>]
[--sort=rootid,gen,ogen,path] <path>
List the subvolumes present in the filesystem <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.
Options
-p
print parent ID.
-a
print all the subvolumes in the filesystem and distinguish
between absolute and relative path with respect to the given
<path>.
-c
print the ogeneration of the subvolume, aliases: ogen or origin
generation.
-g
print the generation of the subvolume.
-o
print only subvolumes bellow specified <path>.
-u
print the UUID of the subvolume.
-q
print the parent uuid of subvolumes (and snapshots).
-t
print the result as a table.
-s
only snapshot subvolumes in the filesystem will be listed.
-r
only readonly subvolumes in the filesystem will be listed.
-G [+|-]<value>
list subvolumes in the filesystem that its generation is >=, <=
or = value. '+' means >= value, '-' means <= value, If there is
neither '+' nor '-', it means = value.
-C [+|-]<value>
list subvolumes in the filesystem that its ogeneration is >=,
<= or = value. The usage is the same to -g option.
--sort=rootid,gen,ogen,path
list subvolumes in order by specified items. you can add '+' or
'-' in front of each items, '+' means ascending, '-' means
descending. The default is ascending.
for --sort you can combine some items together by ',', just
like -sort=+ogen,-gen,path,rootid.
snapshot [-r] <source> <dest>|[<dest>/]<name>
Create a writable/readonly snapshot of the subvolume <source> with
the name <name> in the <dest> directory.
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.
get-default <path>
Get the default subvolume of the filesystem <path>.
The output format is similar to subvolume list command.
set-default <id> <path>
Set the subvolume of the filesystem <path> which is mounted as
default.
The subvolume is identified by <id>, which is returned by the
subvolume list command.
find-new <subvolume> <last_gen>
List the recently modified files in a subvolume, after <last_gen>
ID.
show <path>
Show information of a given subvolume in the <path>.
EXIT STATUS
btrfs subvolume returns a zero exist status if it succeeds. Non zero 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 ALSOmkfs.btrfs(8), btrfs-subvolume(8), btrfs-quota(8), btrfs-qgroup(8),
Btrfs v3.14.2 05/30/2014 BTRFS-SUBVOLUME(8)