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Difference between revisions of "Btrfs"
How to balance metadata
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=== After changing RAID-level === <!--T:64--> | === After changing RAID-level === <!--T:64--> | ||
When you changed RAID-levels (for example from RAID 0 to RAID 1) there is no automatic duplication of the chunks. Only when writing further, btrfs will respect the changed RAID-level. This may not be what you intended. To complete the conversion to another RAID-level you need to tell btrfs to rewrite chunks where needed. You do this with a manual balance: | When you changed RAID-levels (for example from RAID 0 to RAID 1) there is no automatic duplication of the chunks. Only when writing further, btrfs will respect the changed RAID-level. This may not be what you intended. To complete the conversion to another RAID-level you need to tell btrfs to rewrite chunks where needed. You do this with a manual balance: | ||
=== Metadata === | |||
It is rarely recommended to include blocks with metadata in a balance. It is advantageous, in exceptional cases, if the following conditions are currently met: | |||
You can check with: | |||
{{RootCmd|command=sudo btrfs fi us /|grep 'Meta.*Size'}} | |||
{{ic|Metadata,RAID1: Size:9.00GiB, Used:6.58GiB (73.09%)}} | |||
* Several GB of metadata are present in your filesystem (''6.6 GB present, 9 GB used'') | |||
* This metadata is poorly distributed (''73%'') | |||
* Significantly more than one full GB could become free (9 GB - 6.6 GB ==> ''2.4 GB could become free'') | |||
The command is then: | |||
{{RootCmd|command=btrfs balance start -musage=95 /}} | |||
Btrfs had to move 9 GB of metadata to free up 1 GB ! | |||
{{ic|Metadata,RAID1: Size:8.00GiB, Used:6.58GiB (82.20%)}} | |||
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