Hello,
I have 4 harddisks with 3TB capacity each. They are all used in a btrfs RAID 5.
It has come to my attention, that there
seem to be major flaws in btrfs' raid 5 implementation. Because of that, I want
to convert the the raid 5 to a raid 10
and I have several questions.
* Is that possible as an online conversion?
* Since my effective capacity will shrink during conversions, does btrfs check
if there is enough free capacity to
convert? As you see below, right now it's probably too full, but I'm going to
delete some stuff.
* I understand the command to convert is
btrfs balance start -dconvert=raid10 -mconvert=raid10 /mnt
Correct?
* What disks are allowed to fail? My understanding of a raid 10 is like that
disks = {a, b, c, d}
raid0( raid1(a, b), raid1(c, d) )
This way (a XOR b) AND (c XOR d) are allowed to fail without the raid to fail
(either a or b and c or d are allowed to fail)
How is that with a btrfs raid 10?
* Any other advice? ;-)
Thanks a lot,
Florian
Some information of my filesystem:
# btrfs filesystem show /
Label: 'data' uuid: 57e5b9e9-01ae-4f9e-8a3d-9f42204d7005
Total devices 4 FS bytes used 7.57TiB
devid 1 size 2.72TiB used 2.72TiB path /dev/sda4
devid 2 size 2.72TiB used 2.72TiB path /dev/sdb4
devid 3 size 2.72TiB used 2.72TiB path /dev/sdc4
devid 4 size 2.72TiB used 2.72TiB path /dev/sdd4
# btrfs filesystem df /
Data, RAID5: total=8.14TiB, used=7.56TiB
System, RAID5: total=96.00MiB, used=592.00KiB
Metadata, RAID5: total=12.84GiB, used=11.06GiB
GlobalReserve, single: total=512.00MiB, used=0.00B
# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda4 11T 7.6T 597G 93% /
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