Odd rebalancing behavior
I have an external 4-disk enclosure, connected through USB 2.0 (my laptop does not have a USB 3.0 connector, and the eSATA connector somehow does not work); it initially had a 2-disk btrfs soft-RAID1 file system (both data and metadata are RAID1).
I recently added two more disks and did a rebalance. To my surprise it went past the point where all four disks have the same amount of disk usage, and went all the way to the original disks being empty, and the new disks having all the data!
Label: 'media.store' uuid: 4cfd3551-aa85-4399-b872-9238ddb14c97
Total devices 4 FS bytes used 1.22TB
devid 3 size 1.82TB used 1.24TB path /dev/sdb
devid 4 size 1.82TB used 1.24TB path /dev/sdc
devid 2 size 1.82TB used 8.00MB path /dev/sde
devid 1 size 1.82TB used 12.00MB path /dev/sdd
Is this to be expected? Would another rebalance fix it, or should I force-stop it by shutting down when the disk usage is roughly balanced?
This is on Fedora 15 pre-release, x86_64, fully updated, kernel 2.6.38.2-9 and btrfs-progs 0.19-13
Thanks,
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Michel Alexandre Salim GPG key ID: 78884778 () ascii ribbon campaign - against html e-mail /\ www.asciiribbon.org - against proprietary attachments -- test mailing list [email protected] To unsubscribe: https://admin.fedoraproject.org/mailman/listinfo/test
Quoted 17 lines · Michel Alexandre Salim
I have an external 4-disk enclosure, connected through USB 2.0 (my laptop does not have a USB 3.0 connector, and the eSATA connector somehow does not work); it initially had a 2-disk btrfs soft-RAID1 file system (both data and metadata are RAID1).
I recently added two more disks and did a rebalance. To my surprise it went past the point where all four disks have the same amount of disk usage, and went all the way to the original disks being empty, and the new disks having all the data!
Label: 'media.store' uuid: 4cfd3551-aa85-4399-b872-9238ddb14c97
Total devices 4 FS bytes used 1.22TB
devid 3 size 1.82TB used 1.24TB path/dev/sdb
devid 4 size 1.82TB used 1.24TB path/dev/sdc
devid 2 size 1.82TB used 8.00MB path/dev/sde
devid 1 size 1.82TB used 12.00MB path/dev/sdd
Quoted 2 lines
Is this to be expected? Would another rebalance fix it, or should I force-stop it by shutting down when the disk usage is roughly balanced?
Currently this is expected behavior, as the current allocator doesn't distribute the chunks evenly. As soon as the round-robin allocator patch is merged, rebalance will lead to a balanced distribution. It has been posted to the list with the subject 'quasi-round-robin for chunk allocation'.
If you test it, some feedback would be nice.
-Arne
Quoted 6 lines
This is on Fedora 15 pre-release,
x86_64, fully updated, kernel 2.6.38.2-9 and btrfs-progs 0.19-13Thanks,