btrfs-qgroup(8)

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

6       btrfs-qgroup - control the quota group of a btrfs filesystem
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SYNOPSIS

9       btrfs qgroup <subcommand> <args>
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DESCRIPTION

12       btrfs qgroup is used to control quota group (qgroup) of a btrfs
13       filesystem.
14
15           Note
16           To use qgroup you need to enable quota first using btrfs quota
17           enable command.
18
19           Warning
20           Qgroup is not stable yet and will impact performance in current
21           mainline kernel (v3.14 so far).
22

QGROUP

24       Quota groups or qgroup in btrfs make a tree hierarchy, the leaf qgroups
25       are attached to subvolumes. The size limits are set per qgroup and
26       apply when any limit is reached in tree that contains a given
27       subvolume.
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29       The limits are separated between shared and exclusive and reflect the
30       extent ownership. For example a fresh snapshot shares almost all the
31       blocks with the original subvolume, new writes to either subvolume will
32       raise towards the exclusive limit.
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34       The qgroup identifiers conform to level/id where level 0 is reserved to
35       the qgroups associated with subvolumes. Such qgroups are created
36       automatically.
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38       The qgroup hierarchy is built by commands create and assign.
39
40           Note
41           If the qgroup of a subvolume is destroyed, quota about the
42           subvolume will not be functional until qgroup 0/<subvolume id> is
43           created again.
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SUBCOMMAND

46       assign [options] <src> <dst> <path>
47           Assign qgroup <src> as the child qgroup of <dst> in the btrfs
48           filesystem identified by <path>.
49
50           Options
51
52           --rescan
53               Automatically schedule quota rescan if the new qgroup
54               assignment leads to quota inconsistency.
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56           --no-rescan
57               Explicitly ask not to do a rescan.
58
59       create <qgroupid> <path>
60           Create a subvolume quota group.
61
62           For the 0/<subvolume id> qgroup, a qgroup can be created even
63           before the subvolume created.
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65       destroy <qgroupid> <path>
66           Destroy a qgroup.
67
68           If a qgroup is no isolated,which means it is a parent or child
69           qgroup, it can’t be destroyed.
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71       limit [options] <size>|none [<qgroupid>] <path>
72           Limit the size of a qgroup to <size> or no limit in the btrfs
73           filesystem identified by <path>.
74
75           If <qgroupid> is not given, qgroup of the subvolume identified by
76           <path> is used if possible.
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78           Options
79
80           -c
81               limit amount of data after compression. This is the default, it
82               is currently not possible to turn off this option.
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84           -e
85               limit space exclusively assigned to this qgroup.
86
87       remove <src> <dst> <path>
88           Remove the relationship between child qgroup <src> and parent
89           qgroup <dst> in the btrfs filesystem identified by <path>.
90
91       show [options] <path>
92           Show all qgroups in the btrfs filesystem identified by <path>.
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94           Options
95
96           -p
97               print parent qgroup id.
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99           -c
100               print child qgroup id.
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102           -r
103               print limit of referenced size of qgroup.
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105           -e
106               print limit of exclusive size of qgroup.
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108           -F
109               list all qgroups which impact the given path(include ancestral
110               qgroups)
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112           -f
113               list all qgroups which impact the given path(exclude ancestral
114               qgroups)
115
116           --raw
117               raw numbers in bytes, without the B suffix.
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119           --human-readable
120               print human friendly numbers, base 1024, this is the default
121
122           --iec
123               select the 1024 base for the following options, according to
124               the IEC standard.
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126           --si
127               select the 1000 base for the following options, according to
128               the SI standard.
129
130           --kbytes
131               show sizes in KiB, or kB with --si.
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133           --mbytes
134               show sizes in MiB, or MB with --si.
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136           --gbytes
137               show sizes in GiB, or GB with --si.
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139           --tbytes
140               show sizes in TiB, or TB with --si.
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142           --sort=[+/-]<attr>[,[+/-]<attr>]...
143               list qgroups in order of <attr>.
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145               <attr> can be one or more of
146               qgroupid,rfer,excl,max_rfer,max_excl.
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148               Prefix '+' means ascending order and '-' means descending order
149               of <attr>. If no prefix is given, use ascending order by
150               default.
151
152               If multiple <attr>s is given, use comma to separate.
153
154           --sync
155               To retrieve information after updating the state of qgroups,
156               force sync of the filesystem identified by <path> before
157               getting information.
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EXIT STATUS

160       btrfs qgroup returns a zero exit status if it succeeds. Non zero is
161       returned in case of failure.
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AVAILABILITY

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