150 lines
4.2 KiB
Plaintext
150 lines
4.2 KiB
Plaintext
btrfs-qgroup(8)
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===============
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NAME
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----
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btrfs-qgroup - control the quota group of a btrfs filesystem
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SYNOPSIS
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--------
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*btrfs qgroup* <subcommand> <args>
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DESCRIPTION
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-----------
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*btrfs qgroup* is used to control quota group (qgroup) of a btrfs filesystem.
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NOTE: To use qgroup you need to enable quota first using *btrfs quota enable*
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command.
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WARNING: Qgroup is not stable yet and will impact performance in current mainline
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kernel (v3.14 so far).
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QGROUP
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------
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Quota groups or qgroup in btrfs make a tree hierarchy, the leaf qgroups are
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attached to subvolumes. The size limits are set per qgroup and apply when any
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limit is reached in tree that contains a given subvolume.
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The limits are separated between shared and exclusive and reflect the extent
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ownership. For example a fresh snapshot shares almost all the blocks with the
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original subvolume, new writes to either subvolume will raise towards the
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exclusive limit.
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The qgroup identifiers conform to 'level/id' where level 0 is reserved to the
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qgroups associated with subvolumes. Such qgroups are created automatically.
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The qgroup hierarchy is built by commands *create* and *assign*.
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NOTE: If the qgroup of a subvolume is destroyed, quota about the subvolume
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will not be functional until qgroup '0/<subvolume id>' is created again.
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SUBCOMMAND
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----------
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*assign* [options] <src> <dst> <path>::
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Assign qgroup <src> as the child qgroup of <dst> in the btrfs filesystem
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identified by <path>.
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+
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`Options`
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+
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--rescan::::
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Automatically schedule quota rescan if the new qgroup assignment leads to
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quota inconsistency.
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--no-rescan::::
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Explicitly ask not to do a rescan.
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*create* <qgroupid> <path>::
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Create a subvolume quota group.
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+
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For the '0/<subvolume id>' qgroup, a qgroup can be created even before the
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subvolume created.
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*destroy* <qgroupid> <path>::
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Destroy a qgroup.
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+
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If a qgroup is no isolated,which means it is a parent or child qgroup, it
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can't be destroyed.
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*limit* [options] <size>|none [<qgroupid>] <path>::
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Limit the size of a qgroup to <size> or no limit in the btrfs filesystem
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identified by <path>.
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+
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If <qgroupid> is not given, qgroup of the subvolume identified by <path>
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is used if possible.
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+
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`Options`
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+
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-c::::
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limit amount of data after compression. This is the default, it is currently not
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possible to turn off this option.
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+
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-e::::
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limit space exclusively assigned to this qgroup.
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*remove* <src> <dst> <path>::
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Remove the relationship between child qgroup <src> and parent qgroup <dst> in
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the btrfs filesystem identified by <path>.
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*show* [options] <path>::
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Show all qgroups in the btrfs filesystem identified by <path>.
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+
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`Options`
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+
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-p::::
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print parent qgroup id.
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-c::::
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print child qgroup id.
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-r::::
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print limit of referenced size of qgroup.
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-e::::
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print limit of exclusive size of qgroup.
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-F::::
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list all qgroups which impact the given path(include ancestral qgroups)
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-f::::
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list all qgroups which impact the given path(exclude ancestral qgroups)
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--raw::::
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raw numbers in bytes, without the 'B' suffix.
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--human-readable::::
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print human friendly numbers, base 1024, this is the default
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--iec::::
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select the 1024 base for the following options, according to the IEC standard.
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--si::::
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select the 1000 base for the following options, according to the SI standard.
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--kbytes::::
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show sizes in KiB, or kB with --si.
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--mbytes::::
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show sizes in MiB, or MB with --si.
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--gbytes::::
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show sizes in GiB, or GB with --si.
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--tbytes::::
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show sizes in TiB, or TB with --si.
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--sort=[\+/-]<attr>[,[+/-]<attr>]...::::
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list qgroups in order of <attr>.
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+
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<attr> can be one or more of qgroupid,rfer,excl,max_rfer,max_excl.
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+
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Prefix \'+' means ascending order and \'-' means descending order of <attr>.
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If no prefix is given, use ascending order by default.
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+
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If multiple <attr>s is given, use comma to separate.
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+
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--sync::::
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To retrieve information after updating the state of qgroups,
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force sync of the filesystem identified by <path> before getting information.
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EXIT STATUS
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-----------
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*btrfs qgroup* returns a zero exit status if it succeeds. Non zero is
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returned in case of failure.
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AVAILABILITY
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------------
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*btrfs* is part of btrfs-progs.
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Please refer to the btrfs wiki http://btrfs.wiki.kernel.org for
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further details.
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SEE ALSO
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--------
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`mkfs.btrfs`(8),
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`btrfs-subvolume`(8),
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`btrfs-quota`(8),
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