On Fri, 2011-04-01 at 14:12 +0200, Helmut Hullen wrote:
> Hallo, Struan,
>
> Du meintest am 01.04.11:
>
> > 1) Is the balancing operation expected to take many hours (or days?)
> > on a filesystem such as this? Or are there known issues with the
> > algorithm that are yet to be addressed?
>
> May be. Balancing about 15 GByte needed about 2 hours (or less),
> balancing about 2 TByte needed about 20 hours.
[...]
I've got a balance running since Monday on a 9TB volume (3.5 of which
are used, 3.2 allegedly free), showing no sign of finishing soon. Should
I be worried?
Using /proc/sys/vm/block_dump, I can see it's seeking all over the
place, which is probably why throughput is not high. I can also see it
writing several times to the same sectors.
# df -h /backup
Filesystem Size Used Avail Use% Mounted on
/dev/sda4 8.2T 3.5T 3.2T 53% /backup
# btrfs fi sh
Label: none uuid: ...
Total devices 3 FS bytes used 3.43TB
devid 4 size 2.73TB used 1.16TB path /dev/sdc
devid 3 size 2.73TB used 1.16TB path /dev/sdb
devid 2 size 2.70TB used 1.14TB path /dev/sda4
Btrfs Btrfs v0.19
# ps -eolstart,args | grep balance
Mon Mar 28 11:18:18 2011 sudo btrfs fi balance /backup
Mon Mar 28 11:18:18 2011 btrfs fi balance /backup
# date
Fri Apr 1 19:28:40 BST 2011
# btrfs fi df /backup
Data, RAID0: total=3.41TB, used=3.41TB
System, RAID1: total=16.00MB, used=232.00KB
Metadata, RAID1: total=27.75GB, used=20.47GB
# iostat -md
Device: tps MB_read/s MB_wrtn/s MB_read MB_wrtn
sda 14.49 2.37 2.39 903123 913112
sdc 501.23 2.68 5.06 1022456 1928462
sdb 477.28 2.58 5.06 982853 1928482
It's already written more than the used space.
Cheers,
Stephane
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