On 07/17/2013 21:56, Dan van der Ster wrote:
Well, I'm trying a balance again with -dconvert=raid6 -dusage=5 this
time. Will report back...
On Wed, Jul 17, 2013 at 3:34 PM, Dan van der Ster <dan@xxxxxxxxxxxxxx> wrote:
Hi,
Two days ago I decided to throw caution to the wind and convert my
raid1 array to raid6, for the space and redundancy benefits. I did
# btrfs fi balance start -dconvert=raid6 /media/btrfs
Eventually today the balance finished, but the conversion to raid6 was
incomplete:
# btrfs fi df /media/btrfs
Data, RAID1: total=693.00GB, used=690.47GB
Data, RAID6: total=6.36TB, used=4.35TB
System, RAID1: total=32.00MB, used=1008.00KB
System: total=4.00MB, used=0.00
Metadata, RAID1: total=8.00GB, used=6.04GB
A recent btrfs balance status (before finishing) said:
# btrfs balance status /media/btrfs
Balance on '/media/btrfs' is running
4289 out of about 5208 chunks balanced (4988 considered), 18% left
and at the end I have:
[164935.053643] btrfs: 693 enospc errors during balance
Here is the array:
# btrfs fi show /dev/sdb
Label: none uuid: 743135d0-d1f5-4695-9f32-e682537749cf
Total devices 7 FS bytes used 5.04TB
devid 2 size 2.73TB used 2.73TB path /dev/sdh
devid 1 size 2.73TB used 2.73TB path /dev/sdg
devid 5 size 1.36TB used 1.31TB path /dev/sde
devid 6 size 1.36TB used 1.31TB path /dev/sdf
devid 4 size 1.82TB used 1.82TB path /dev/sdd
devid 3 size 1.82TB used 1.82TB path /dev/sdc
devid 7 size 1.82TB used 1.82TB path /dev/sdb
I'm running latest stable, plus the patch "free csums when we're done
scrubbing an extent" (otherwise I get OOM when scrubbing).
# uname -a
Linux dvanders-webserver 3.10.1+ #1 SMP Mon Jul 15 17:07:19 CEST 2013
x86_64 x86_64 x86_64 GNU/Linux
I still have plenty of free space:
# df -h /media/btrfs
Filesystem Size Used Avail Use% Mounted on
/dev/sdd 14T 5.8T 2.2T 74% /media/btrfs
Any idea how I can get out of this? Thanks!
You know the limitations of the current Btrfs RAID5/6 implementation,
don't you? No protection against power loss or disk failures. No support
for scrub. These limits are explained very explicitly in the commit message:
http://lwn.net/Articles/536038/
I'd recommend Btrfs RAID1 for the time being.
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