# btrfs-subvolume

## 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 its own independent
           file/directory hierarchy. Subvolumes can share file extents. A
           snapshot is also subvolume, but with a given initial content of
           the original subvolume.
    
               **Note**
    
               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:
    
           •   like any other directory that is accessible to the user
    
           •   like a separately mounted filesystem (options _subvol_ or
               _subvolid_)
    
           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>_
               Create a subvolume _< name>_ in _< dest>_.
    
               If _< dest>_ is not given, subvolume _< name>_ will be created in
               the current directory.
    
               **Options**
    
               -i _< qgroupid>_
                   Add the newly created subvolume to a qgroup. This option
                   can be given multiple times.
    
           **delete**[options] _<[<subvolume>_ [_< subvolume>_...]], **delete**
           -i|--subvolid _< subvolid> <path>_>
               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.
    
               If --subvolid is used, _< path>_ must point to a btrfs
               filesystem. See **btrfs subvolume list** or **btrfs inspect-internal**
               **rootid** how to get the subvolume id.
    
               The corresponding directory is removed instantly but the data
               blocks are removed later in the background. The command
               returns immediately. See **btrfs subvolume sync** how to wait
               until the subvolume gets completely removed.
    
               The deletion does not involve full transaction 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 device.
    
               The default subvolume (see **btrfs subvolume set-default**) cannot
               be deleted and returns error (EPERM) and this is logged to the
               system log. A subvolume that’s currently involved in send (see
               **btrfs send**) also cannot be deleted until the send is finished.
               This is also logged in the system log.
    
               **Options**
    
               -c|--commit-after
                   wait for transaction commit at the end of the operation.
    
               -C|--commit-each
                   wait for transaction commit after deleting each subvolume.
    
               -i|--subvolid _< subvolid>_
                   subvolume id to be removed instead of the _< path>_ that
                   should point to the filesystem with the subvolume
    
               -v|--verbose
                   (deprecated) alias for global _-v_ option
    
           **find-new** _< subvolume> <last_gen>_
               List the recently modified files in a subvolume, after
               _< last_gen>_ generation.
    
           **get-default** _< path>_
               Get the default subvolume of the filesystem _< path>_.
    
               The output format is similar to **subvolume list** command.
    
           **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>_ gen _< generation>_ top level _< ID>_ path _< path>_
    
               where ID is subvolume’s id, gen is an internal counter which
               is updated every transaction, top level is the same as parent
               subvolume’s id, and 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.
    
               **Options**
    
               Path filtering
    
                   -o
                       print only subvolumes below specified _< path>_.
    
                   -a
                       print all the subvolumes in the filesystem and
                       distinguish between absolute and relative path with
                       respect to the given _< path>_.
    
               Field selection
    
                   -p
                       print the parent ID (_parent_ here means the subvolume
                       which contains this subvolume).
    
                   -c
                       print the ogeneration of the subvolume, aliases: ogen
                       or origin generation.
    
                   -g
                       print the generation of the subvolume (default).
    
                   -u
                       print the UUID of the subvolume.
    
                   -q
                       print the parent UUID of the subvolume (_parent_ here
                       means subvolume of which this subvolume is a
                       snapshot).
    
                   -R
                       print the UUID of the sent subvolume, where the
                       subvolume is the result of a receive operation.
    
               Type filtering
    
                   -s
                       only snapshot subvolumes in the filesystem will be
                       listed.
    
                   -r
                       only readonly subvolumes in the filesystem will be
                       listed.
    
                   -d
                       list deleted subvolumes that are not yet cleaned.
    
               Other
    
                   -t
                       print the result as a table.
    
               Sorting
                   By default the subvolumes will be sorted by subvolume ID
                   ascending.
    
                   -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.
    
           **set-default**[_< subvolume>_|_< id> <path>_]
               Set the default subvolume for the (mounted) filesystem.
    
               Set the default subvolume for the (mounted) filesystem at
               _< path>_. This will hide the top-level subvolume (i.e. the one
               mounted with _subvol=/_ or _subvolid=5_). Takes action on next
               mount.
    
               There are two ways how to specify the subvolume, by _< id>_ or by
               the _< subvolume>_ path. The id can be obtained from **btrfs**
               **subvolume list** , **btrfs subvolume show** or **btrfs inspect-internal**
               **rootid**.
    
           **show**[options] _< path>_
               Show more information about a subvolume (UUIDs, generations,
               times, flags, related snapshots).
    
                   /mnt/btrfs/subvolume
                           Name:                   subvolume
                           UUID:                   5e076a14-4e42-254d-ac8e-55bebea982d1
                           Parent UUID:            -
                           Received UUID:          -
                           Creation time:          2018-01-01 12:34:56 +0000
                           Subvolume ID:           79
                           Generation:             2844
                           Gen at creation:        2844
                           Parent ID:              5
                           Top level ID:           5
                           Flags:                  -
                           Snapshot(s):
    
               **Options**
    
               -r|--rootid _< ID>_
                   show details about subvolume with root _< ID>_, looked up in
                   _< path>_
    
               -u|--uuid UUID
                   show details about subvolume with the given _< UUID>_, looked
                   up in _< path>_
    
           **snapshot**[-r] [-i _< qgroupid>_] _< source> <dest>_|[<dest>/]_< name>_
               Create a 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.
    
               **Options**
    
               -r
                   Make the new snapshot read only.
    
               -i _< qgroupid>_
                   Add the newly created subvolume to a qgroup. This option
                   can be given multiple times.
    
           **sync** _< path>_ [subvolid...]
               Wait until given subvolume(s) are completely removed from the
               filesystem after deletion. If no subvolume id is given, wait
               until all current deletion requests are completed, but do not
               wait for subvolumes deleted in the meantime.
    
               **Options**
    
               -s _< N>_
                   sleep N seconds between checks (default: 1)
    


## SUBVOLUME FLAGS



           The subvolume flag currently implemented is the _ro_ property.
           Read-write subvolumes have that set to _false_ , snapshots as _true_.
           In addition to that, a plain snapshot will also have last change
           generation and creation generation equal.
    
           Read-only snapshots are building blocks fo incremental send (see
           btrfs-send(8)) and the whole use case relies on unmodified
           snapshots where the relative changes are generated from. Thus,
           changing the subvolume flags from read-only to read-write will
           break the assumptions and may lead to unexpected changes in the
           resulting incremental stream.
    
           A snapshot that was created by send/receive will be read-only,
           with different last change generation, read-only and with set
           _received_uuid_ which identifies the subvolume on the filesystem
           that produced the stream. The usecase relies on matching data on
           both sides. Changing the subvolume to read-write after it has been
           received requires to reset the _received_uuid_. As this is a notable
           change and could potentially break the incremental send use case,
           performing it by **btrfs property set** requires force if that is
           really desired by user.
    
               **Note**
    
               The safety checks have been implemented in 5.14.2, any
               subvolumes previously received (with a valid _received_uuid_)
               and read-write status may exist and could still lead to
               problems with send/receive. You can use **btrfs subvolume show**
               to identify them. Flipping the flags to read-only and back to
               read-write will reset the _received_uuid_ manually. There may
               exist a convenience tool in the future.
    


## EXAMPLES



           **Example 1. Deleting a subvolume**
    
           If we want to delete a subvolume called **foo** from a btrfs volume
           mounted at **/mnt/bar** we could run the following:
    
               btrfs subvolume delete /mnt/bar/foo
    


## 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.


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