141 lines
4.4 KiB
Plaintext
141 lines
4.4 KiB
Plaintext
btrfs-balance(8)
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================
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NAME
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----
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btrfs-balance - balance btrfs filesystem
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SYNOPSIS
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--------
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*btrfs balance* <subcommand> <args>
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DESCRIPTION
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-----------
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*btrfs balance* is used to balance chunks in a btrfs filesystem across
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multiple or even single device.
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See `btrfs-device`(8) for more details about the effect on device management.
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NOTE: The balance subcommand also exists under the *filesystem* namespace. This
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still works for backward compatibility but is deprecated and should not be
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used anymore.
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NOTE: A short syntax *btrfs balance <path>* works due to backward compatibility
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but is deprecated and should not be used anymore. Use *btrfs balance start*
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command instead.
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SUBCOMMAND
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----------
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*cancel* <path>::
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Cancel running or paused balance.
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*pause* <path>::
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Pause running balance.
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*resume* <path>::
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Resume interrupted balance.
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*start* [options] <path>::
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Balance chunks across the devices *online*.
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+
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Balance and/or convert (change allocation profile of) chunks that
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passed all filters in a comma-separated list of filters for a
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particular chunk type.
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If filter list is not given balance all chunks of that type.
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In case none of the -d, -m or -s options is
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given balance all chunks in a filesystem.
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+
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`Options`
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-d[<filters>]::::
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act on data chunks. See `FILTERS` section for details about <filters>.
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-m[<filters>]::::
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act on metadata chunks. See `FILTERS` section for details about <filters>.
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-s[<filters>]::::
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act on system chunks (only under -f). See `FILTERS` section for details about <filters>.
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-v::::
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be verbose
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-f::::
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force reducing of metadata integrity
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*status* [-v] <path>::
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Show status of running or paused balance.
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+
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If '-v' option is given, output will be verbose.
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FILTERS
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-------
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From kernel 3.3 onwards, btrfs balance can limit its action to a subset of the
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full filesystem, and can be used to change the replication configuration (e.g.
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moving data from single to RAID-1). This functionality is accessed through the
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'-d', '-m' or '-s' options to btrfs balance start, which filter on data,
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metadata and system blocks respectively.
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A filter has the following stucture: ::
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'type'[='params'][,'type'=...]
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The available types are:
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*profiles*::
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Balances only block groups with the given replication profiles. Parameters
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are a list of profile names separated by |.
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*usage*::
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Balances only block groups with usage under the given percentage. The
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value of 0 is allowed and will clean up completely unused block groups, this
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should not require any new space allocated. You may want to use usage=0 in
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case balance is returnin ENOSPC and your filesystem is not too full.
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*devid*::
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Balances only block groups which have at least one chunk on the given
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device (by btrfs device ID -- use btrfs fi show to list device IDs)
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*drange*::
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Balances only block groups which overlap with the given byte range on any
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device. (Use in conjunction with "devid" to filter on a specific device). The
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parameter is a range specified as <start..end>.
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*vrange*::
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Balances only block groups which overlap with the given byte range in the
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filesystem's internal virtual address space. This is the address space that
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most reports from btrfs in the kernel log use. The parameter is a range
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specified as <start..end>.
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*convert*::
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Convert each selected block group to the given profile name identified by
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parameters.
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*limit*::
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Process only given number of chunks, after all filters apply. This can be used
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to specifically target a chunk in connection with other filters (drange,
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vrange) or just simply limit the amount of work done by a single balance run.
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*soft*::
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Takes no parameters. Only has meaning when converting between profiles.
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When doing convert from one profile to another and soft mode is on,
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restriper won't touch chunks that already have the target profile. This is
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useful if e.g. half of the FS was converted earlier.
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+
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The soft mode switch is (like every other filter) per-type. This means
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that we can convert for example meta chunks the "hard" way while converting
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data chunks selectively with soft switch.
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Profile names, used in profiles and convert are one of: 'raid0', 'raid1',
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'raid10', 'raid5', 'raid6', 'dup', 'single'.
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EXIT STATUS
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-----------
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*btrfs balance* 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-device`(8)
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