2011/10/15 Martin Mailand <mar...@tuxadero.com>:
> Hi Christian,
> I have a very similar experience, I also used josef's tree and btrfs snaps =
> 0, the next problem I had than was excessive fragmentation, so I  used this
> patch http://marc.info/?l=linux-btrfs&m=131495014823121&w=2, and changed the
> btrfs option to (btrfs options = noatime,nodatacow,autodefrag) that kept the
> fragmentation under control.
> But even with this setup after a few days the load on the osd is unbearable.

How did you find out about our fragmentation issues? Was it just a
performance problem?

> As far as I understood the doku if you disable the btrfs snapshot
> functionality the writeahead journal is activated.
> http://ceph.newdream.net/wiki/Ceph.conf
> And I get this in the logs.
> mount: enabling WRITEAHEAD journal mode: 'filestore btrfs snap' mode is not
> enabled
>
> May I asked what kind of probs you did have with ext4? Because I am looking
> into this direction as well.

You can read about our ext4 problems here:

http://marc.info/?l=ceph-devel&m=131201869703245&w=2

Our bugreport with RedHat didn't make any progress for a long time,
but last week RedHat made two sugestions:

- If you configure ceph with 'filestore flusher = false', do you see
any different behavior?
- If you mount with -o noauto_da_alloc does it change anything?

Since I have just migrated to btrfs, I've some problems to check this,
but I'll try to do this as soon as I can get hold of some extra
hardware.

Regards,
Christian
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