1BTRFS-SUBVOLUME(8)               Btrfs Manual               BTRFS-SUBVOLUME(8)
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NAME

6       btrfs-subvolume - manage btrfs subvolumes
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SYNOPSIS

9       btrfs subvolume <subcommand> [<args>]
10

DESCRIPTION

12       btrfs subvolume is used to create/delete/list/show btrfs subvolumes and
13       snapshots.
14

SUBVOLUME AND SNAPSHOT

16       A subvolume is a part of filesystem with its own independent
17       file/directory hierarchy. Subvolumes can share file extents. A snapshot
18       is also subvolume, but with a given initial content of the original
19       subvolume.
20
21           Note
22           A subvolume in btrfs is not like an LVM logical volume, which is
23           block-level snapshot while btrfs subvolumes are file extent-based.
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25       A subvolume looks like a normal directory, with some additional
26       operations described below. Subvolumes can be renamed or moved, nesting
27       subvolumes is not restricted but has some implications regarding
28       snapshotting.
29
30       A subvolume in btrfs can be accessed in two ways:
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32       •   like any other directory that is accessible to the user
33
34       •   like a separately mounted filesystem (options subvol or subvolid)
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36       In the latter case the parent directory is not visible and accessible.
37       This is similar to a bind mount, and in fact the subvolume mount does
38       exactly that.
39
40       A freshly created filesystem is also a subvolume, called top-level,
41       internally has an id 5. This subvolume cannot be removed or replaced by
42       another subvolume. This is also the subvolume that will be mounted by
43       default, unless the default subvolume has been changed (see subcommand
44       set-default).
45
46       A snapshot is a subvolume like any other, with given initial content.
47       By default, snapshots are created read-write. File modifications in a
48       snapshot do not affect the files in the original subvolume.
49

SUBCOMMAND

51       create [-i <qgroupid>] [<dest>/]<name>
52           Create a subvolume <name> in <dest>.
53
54           If <dest> is not given, subvolume <name> will be created in the
55           current directory.
56
57           Options
58
59           -i <qgroupid>
60               Add the newly created subvolume to a qgroup. This option can be
61               given multiple times.
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63       delete [options] <[<subvolume> [<subvolume>...]], delete -i|--subvolid
64       <subvolid> <path>>
65           Delete the subvolume(s) from the filesystem.
66
67           If <subvolume> is not a subvolume, btrfs returns an error but
68           continues if there are more arguments to process.
69
70           If --subvolid is used, <path> must point to a btrfs filesystem. See
71           btrfs subvolume list or btrfs inspect-internal rootid how to get
72           the subvolume id.
73
74           The corresponding directory is removed instantly but the data
75           blocks are removed later in the background. The command returns
76           immediately. See btrfs subvolume sync how to wait until the
77           subvolume gets completely removed.
78
79           The deletion does not involve full transaction commit by default
80           due to performance reasons. As a consequence, the subvolume may
81           appear again after a crash. Use one of the --commit options to wait
82           until the operation is safely stored on the device.
83
84           The default subvolume (see btrfs subvolume set-default) cannot be
85           deleted and returns error (EPERM) and this is logged to the system
86           log. A subvolume that’s currently involved in send (see btrfs send)
87           also cannot be deleted until the send is finished. This is also
88           logged in the system log.
89
90           Options
91
92           -c|--commit-after
93               wait for transaction commit at the end of the operation.
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95           -C|--commit-each
96               wait for transaction commit after deleting each subvolume.
97
98           -i|--subvolid <subvolid>
99               subvolume id to be removed instead of the <path> that should
100               point to the filesystem with the subvolume
101
102           -v|--verbose
103               (deprecated) alias for global -v option
104
105       find-new <subvolume> <last_gen>
106           List the recently modified files in a subvolume, after <last_gen>
107           generation.
108
109       get-default <path>
110           Get the default subvolume of the filesystem <path>.
111
112           The output format is similar to subvolume list command.
113
114       list [options] [-G [+|-]<value>] [-C [+|-]<value>]
115       [--sort=rootid,gen,ogen,path] <path>
116           List the subvolumes present in the filesystem <path>.
117
118           For every subvolume the following information is shown by default:
119
120           ID <ID> gen <generation> top level <ID> path <path>
121
122           where ID is subvolume’s id, gen is an internal counter which is
123           updated every transaction, top level is the same as parent
124           subvolume’s id, and path is the relative path of the subvolume to
125           the top level subvolume. The subvolume’s ID may be used by the
126           subvolume set-default command, or at mount time via the subvolid=
127           option.
128
129           Options
130
131           Path filtering
132
133               -o
134                   print only subvolumes below specified <path>.
135
136               -a
137                   print all the subvolumes in the filesystem and distinguish
138                   between absolute and relative path with respect to the
139                   given <path>.
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141           Field selection
142
143               -p
144                   print the parent ID (parent here means the subvolume which
145                   contains this subvolume).
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147               -c
148                   print the ogeneration of the subvolume, aliases: ogen or
149                   origin generation.
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151               -g
152                   print the generation of the subvolume (default).
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154               -u
155                   print the UUID of the subvolume.
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157               -q
158                   print the parent UUID of the subvolume (parent here means
159                   subvolume of which this subvolume is a snapshot).
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161               -R
162                   print the UUID of the sent subvolume, where the subvolume
163                   is the result of a receive operation.
164
165           Type filtering
166
167               -s
168                   only snapshot subvolumes in the filesystem will be listed.
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170               -r
171                   only readonly subvolumes in the filesystem will be listed.
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173               -d
174                   list deleted subvolumes that are not yet cleaned.
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176           Other
177
178               -t
179                   print the result as a table.
180
181           Sorting
182               By default the subvolumes will be sorted by subvolume ID
183               ascending.
184
185               -G [+|-]<value>
186                   list subvolumes in the filesystem that its generation is
187                   >=, ⟨ or = value. '+' means >= value, '-' means <= value,
188                   If there is neither '+' nor '-', it means = value.
189
190               -C [+|-]<value>
191                   list subvolumes in the filesystem that its ogeneration is
192                   >=, <= or = value. The usage is the same to -G option.
193
194               --sort=rootid,gen,ogen,path
195                   list subvolumes in order by specified items. you can add
196                   '+' or '-' in front of each items, '+' means ascending, '-'
197                   means descending. The default is ascending.
198
199                   for --sort you can combine some items together by ',', just
200                   like --sort=+ogen,-gen,path,rootid.
201
202       set-default [<subvolume>|<id> <path>]
203           Set the default subvolume for the (mounted) filesystem.
204
205           Set the default subvolume for the (mounted) filesystem at <path>.
206           This will hide the top-level subvolume (i.e. the one mounted with
207           subvol=/ or subvolid=5). Takes action on next mount.
208
209           There are two ways how to specify the subvolume, by <id> or by the
210           <subvolume> path. The id can be obtained from btrfs subvolume list,
211           btrfs subvolume show or btrfs inspect-internal rootid.
212
213       show [options] <path>
214           Show more information about a subvolume (UUIDs, generations, times,
215           flags, related snapshots).
216
217               /mnt/btrfs/subvolume
218                       Name:                   subvolume
219                       UUID:                   5e076a14-4e42-254d-ac8e-55bebea982d1
220                       Parent UUID:            -
221                       Received UUID:          -
222                       Creation time:          2018-01-01 12:34:56 +0000
223                       Subvolume ID:           79
224                       Generation:             2844
225                       Gen at creation:        2844
226                       Parent ID:              5
227                       Top level ID:           5
228                       Flags:                  -
229                       Snapshot(s):
230
231           Options
232
233           -r|--rootid <ID>
234               show details about subvolume with root <ID>, looked up in
235               <path>
236
237           -u|--uuid UUID
238               show details about subvolume with the given <UUID>, looked up
239               in <path>
240
241       snapshot [-r] [-i <qgroupid>] <source> <dest>|[<dest>/]<name>
242           Create a snapshot of the subvolume <source> with the name <name> in
243           the <dest> directory.
244
245           If only <dest> is given, the subvolume will be named the basename
246           of <source>. If <source> is not a subvolume, btrfs returns an
247           error.
248
249           Options
250
251           -r
252               Make the new snapshot read only.
253
254           -i <qgroupid>
255               Add the newly created subvolume to a qgroup. This option can be
256               given multiple times.
257
258       sync <path> [subvolid...]
259           Wait until given subvolume(s) are completely removed from the
260           filesystem after deletion. If no subvolume id is given, wait until
261           all current deletion requests are completed, but do not wait for
262           subvolumes deleted in the meantime.
263
264           Options
265
266           -s <N>
267               sleep N seconds between checks (default: 1)
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SUBVOLUME FLAGS

270       The subvolume flag currently implemented is the ro property. Read-write
271       subvolumes have that set to false, snapshots as true. In addition to
272       that, a plain snapshot will also have last change generation and
273       creation generation equal.
274
275       Read-only snapshots are building blocks fo incremental send (see
276       btrfs-send(8)) and the whole use case relies on unmodified snapshots
277       where the relative changes are generated from. Thus, changing the
278       subvolume flags from read-only to read-write will break the assumptions
279       and may lead to unexpected changes in the resulting incremental stream.
280
281       A snapshot that was created by send/receive will be read-only, with
282       different last change generation, read-only and with set received_uuid
283       which identifies the subvolume on the filesystem that produced the
284       stream. The usecase relies on matching data on both sides. Changing the
285       subvolume to read-write after it has been received requires to reset
286       the received_uuid. As this is a notable change and could potentially
287       break the incremental send use case, performing it by btrfs property
288       set requires force if that is really desired by user.
289
290           Note
291           The safety checks have been implemented in 5.14.2, any subvolumes
292           previously received (with a valid received_uuid) and read-write
293           status may exist and could still lead to problems with
294           send/receive. You can use btrfs subvolume show to identify them.
295           Flipping the flags to read-only and back to read-write will reset
296           the received_uuid manually. There may exist a convenience tool in
297           the future.
298

EXAMPLES

300       Example 1. Deleting a subvolume
301
302       If we want to delete a subvolume called foo from a btrfs volume mounted
303       at /mnt/bar we could run the following:
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305           btrfs subvolume delete /mnt/bar/foo
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EXIT STATUS

308       btrfs subvolume returns a zero exit status if it succeeds. A non-zero
309       value is returned in case of failure.
310

AVAILABILITY

312       btrfs is part of btrfs-progs. Please refer to the btrfs wiki
313       http://btrfs.wiki.kernel.org for further details.
314

SEE ALSO

316       mkfs.btrfs(8), mount(8), btrfs-quota(8), btrfs-qgroup(8), btrfs-send(8)
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320Btrfs v5.15.1                     11/22/2021                BTRFS-SUBVOLUME(8)
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