btrfs-progs/Documentation/btrfs-qgroup.asciidoc
Tsutomu Itoh bd1ac1fb1d btrfs-progs: qgroup: add sync option to 'qgroup show'
The 'qgroup show' command does not synchronize filesystem.
Therefore, 'qgroup show' may not display the correct value unless
synchronized with 'filesystem sync' command etc.

So add the '--sync' option so that we can choose whether or not
to synchronize when executing the command.

Signed-off-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2017-01-25 09:48:33 +01:00

150 lines
4.2 KiB
Plaintext

btrfs-qgroup(8)
===============
NAME
----
btrfs-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 you need to enable quota first using *btrfs quota enable*
command.
WARNING: Qgroup is not stable yet and will impact performance in current mainline
kernel (v3.14 so far).
QGROUP
------
Quota groups or qgroup in btrfs make a tree hierarchy, the leaf qgroups are
attached to subvolumes. The size limits are set per qgroup and apply when any
limit is reached in tree that contains a given subvolume.
The limits are separated between shared and exclusive and reflect the extent
ownership. For example a fresh snapshot shares almost all the blocks with the
original subvolume, new writes to either subvolume will raise towards the
exclusive limit.
The qgroup identifiers conform to 'level/id' where level 0 is reserved to the
qgroups associated with subvolumes. Such qgroups are created automatically.
The qgroup hierarchy is built by commands *create* and *assign*.
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* [options] <src> <dst> <path>::
Assign qgroup <src> as the child qgroup of <dst> in the btrfs filesystem
identified by <path>.
+
`Options`
+
--rescan::::
Automatically schedule quota rescan if the new qgroup assignment leads to
quota inconsistency.
--no-rescan::::
Explicitly ask not to do a rescan.
*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.
*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.
+
`Options`
+
-c::::
limit amount of data after compression. This is the default, it is currently not
possible to turn off this option.
+
-e::::
limit space exclusively assigned to this qgroup.
*remove* <src> <dst> <path>::
Remove the relationship between child qgroup <src> and parent qgroup <dst> in
the btrfs filesystem identified by <path>.
*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 limit of referenced size of qgroup.
-e::::
print limit of 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)
--raw::::
raw numbers in bytes, without the 'B' suffix.
--human-readable::::
print human friendly numbers, base 1024, this is the default
--iec::::
select the 1024 base for the following options, according to the IEC standard.
--si::::
select the 1000 base for the following options, according to the SI standard.
--kbytes::::
show sizes in KiB, or kB with --si.
--mbytes::::
show sizes in MiB, or MB with --si.
--gbytes::::
show sizes in GiB, or GB with --si.
--tbytes::::
show sizes in TiB, or TB with --si.
--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.
+
--sync::::
To retrieve information after updating the state of qgroups,
force sync of the filesystem identified by <path> before getting information.
EXIT STATUS
-----------
*btrfs qgroup* returns a zero exit 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 ALSO
--------
`mkfs.btrfs`(8),
`btrfs-subvolume`(8),
`btrfs-quota`(8),