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BTRFS-BALANCE(8) | Btrfs Manual | BTRFS-BALANCE(8) |
NAME¶
btrfs-balance - balance btrfs filesystemSYNOPSIS¶
btrfs [filesystem] balance <subcommand>|<args>DESCRIPTION¶
btrfs balance is used to balance chunks in a btrfs filesystem across multiple or even single device.SUBCOMMAND¶
<path>Balance chunks across the devices
online.
btrfs balance <path> is deprecated, please use
btrfs balance start command instead.
start [options] <path>
Balance chunks across the devices
online.
Balance and/or convert (change allocation profile of) chunks that passed all
filters in a comma-separated list of filters for a particular chunk type. If
filter list is not given balance all chunks of that type. In case none of the
-d, -m or -s options is given balance all chunks in a filesystem.
Options
-d[ <filters>]
pause <path>
act on data chunks. See FILTERS section
for details about <filters>.
-m[ <filters>]
act on metadata chunks. See FILTERS
section for details about <filters>.
-s[ <filters>]
act on system chunks (only under -f). See
FILTERS section for details about <filters>.
-v
be verbose
-f
force reducing of metadata integrity
Pause running balance.
cancel <path>
Cancel running or paused balance.
resume <path>
Resume interrupted balance.
status [-v] <path>
Show status of running or paused balance.
If -v option is given, output will be verbose.
FILTERS¶
From kernel 3.3 onwards, btrfs balance can limit its action to a subset of the full filesystem, and can be used to change the replication configuration (e.g. moving data from single to RAID-1). This functionality is accessed through the -d, -m or -s options to btrfs balance start, which filter on data, metadata and system blocks respectively. A filter has the following stucture:
profiles
Balances only block groups with the given
replication profiles. Parameters are a list of profile names separated by
|.
usage
Balances only block groups with usage under
the given percentage. The value of 0 is allowed and will clean up completely
unused block groups, this should not require any new space allocated. You may
want to use usage=0 in case balance is returnin ENOSPC and your filesystem is
not too full.
devid
Balances only block groups which have at least
one chunk on the given device (by btrfs device ID — use btrfs fi show to
list device IDs)
drange
Balances only block groups which overlap with
the given byte range on any device. (Use in conjunction with "devid"
to filter on a specific device). The parameter is a range specified as
<start..end>.
vrange
Balances only block groups which overlap with
the given byte range in the filesystem’s internal virtual address space.
This is the address space that most reports from btrfs in the kernel log use.
The parameter is a range specified as <start..end>.
convert
Convert each selected block group to the given
profile name identified by parameters.
limit
Process only given number of chunks, after all
filters apply. This can be used to specifically target a chunk in connection
with other filters (drange, vrange) or just simply limit the amount of work
done by a single balance run.
soft
Takes no parameters. Only has meaning when
converting between profiles. When doing convert from one profile to another
and soft mode is on, restriper won’t touch chunks that already have the
target profile. This is useful if e.g. half of the FS was converted earlier.
The soft mode switch is (like every other filter) per-type. This means that we
can convert for example meta chunks the "hard" way while converting
data chunks selectively with soft switch.
EXIT STATUS¶
btrfs balance 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-device(8)06/20/2015 | Btrfs v3.17 |