111 lines
3.1 KiB
Plaintext
111 lines
3.1 KiB
Plaintext
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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, it needs to enable quota first using 'btrfs quota'
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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 group or qgroup in btrfs has its hierarchy like subvolume.
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One subvolume/snapshot can reach its quota limits if it consumes all the quota
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assigned to it or any of the parent qgroup(s).
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Also for snapshot, it consumes no quota initially since all its data
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shares with its parent, so only modification in snapshot consumes quota.
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Every subvolume/snapshot will have its own qgroup with id '0/<subvolume id>'
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upon creating, but can be later destroyed by 'btrfs qgroup destroy' command.
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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' <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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'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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'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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'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 max referenced size of qgroup.
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-e::::
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print max 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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--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 ATTRs is given, use comma to separate.
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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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EXIT STATUS
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-----------
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'btrfs qgroup' returns a zero exist 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. Btrfs filesystem is currently under heavy
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development,
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and not suitable for any uses other than benchmarking and review.
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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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