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Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/btrfs-balance.txt | 60 |
1 files changed, 57 insertions, 3 deletions
diff --git a/Documentation/btrfs-balance.txt b/Documentation/btrfs-balance.txt index 37d8781e..de93c92f 100644 --- a/Documentation/btrfs-balance.txt +++ b/Documentation/btrfs-balance.txt @@ -37,11 +37,11 @@ given balance all chunks in a filesystem. `Options` + -d[<filters>]:::: -act on data chunks +act on data chunks. See `FILTERS` section for details about <filters>. -m[<filters>]:::: -act on metadata chunks +act on metadata chunks. See `FILTERS` section for details about <filters>. -s[<filters>]:::: -act on system chunks (only under -f) +act on system chunks (only under -f). See `FILTERS` section for details about <filters>. -v:::: be verbose -f:::: @@ -61,6 +61,60 @@ 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: :: +'type'[='params'][,'type'=...] + +The available types are: :: +*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. + +*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. + +Profile names, used in profiles and convert are one of: 'raid0', 'raid1', +'raid10', 'raid5', 'raid6', 'dup', 'single'. + EXIT STATUS ----------- *btrfs balance* returns a zero exist status if it succeeds. Non zero is |