BTRFS-QGROUP(8) Btrfs Manual BTRFS-QGROUP(8)NAMEbtrfs-qgroup - control the quota group of a btrfs filesystem
SYNOPSIS
btrfs qgroup <subcommand> <args>
DESCRIPTION
btrfs qgroup is used to control quota group(qgroup) of a btrfs
filesystem.
Note
To use qgroup, it needs to enable quota first using btrfs quota
command.
Warning
Qgroup is not stable yet and will impact performance in current
mainline kernel(v3.14 so far).
QGROUP
Quota group or qgroup in btrfs has its hierarchy like subvolume. One
subvolume/snapshot can reach its quota limits if it consumes all the
quota assigned to it or any of the parent qgroup(s).
Also for snapshot, it consumes no quota initially since all its data
shares with its parent, so only modification in snapshot consumes
quota.
Every subvolume/snapshot will have its own qgroup with id 0/<subvolume
id> upon creating, but can be later destroyed by btrfs qgroup destroy
command.
Note
If the qgroup of a subvolume is destroyed, quota about the
subvolume will not be functional until qgroup 0/<subvolume id> is
created again.
SUBCOMMAND
assign <src> <dst> <path>
Assign qgroup <src> as the child qgroup of <dst> in the btrfs
filesystem identified by <path>.
remove <src> <dst> <path>
Remove the relationship between child qgroup <src> and parent
qgroup <dst> in the btrfs filesystem identified by <path>.
create <qgroupid> <path>
Create a subvolume quota group.
For the 0/<subvolume id> qgroup, a qgroup can be created even
before the subvolume created.
destroy <qgroupid> <path>
Destroy a qgroup.
If a qgroup is no isolated,which means it is a parent or child
qgroup, it can’t be destroyed.
show [options] <path>
Show all qgroups in the btrfs filesystem identified by <path>.
Options
-p
print parent qgroup id.
-c
print child qgroup id.
-r
print max referenced size of qgroup.
-e
print max exclusive size of qgroup.
-F
list all qgroups which impact the given path(include ancestral
qgroups)
-f
list all qgroups which impact the given path(exclude ancestral
qgroups)
--sort=[+/-]<attr>[,[+/-]<attr>]...
list qgroups in order of <attr>.
<attr> can be one or more of
qgroupid,rfer,excl,max_rfer,max_excl.
Prefix '+' means ascending order and '-' means descending order
of <attr>. If no prefix is given, use ascending order by
default.
If multiple <attr>s is given, use comma to separate.
limit [options] <size>|none [<qgroupid>] <path>
Limit the size of a qgroup to <size> or no limit in the btrfs
filesystem identified by <path>.
If <qgroupid> is not given, qgroup of the subvolume identified by
<path> is used if possible.
EXIT STATUS
btrfs qgroup 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 v3.14.2 05/30/2014 BTRFS-QGROUP(8)
