Re: Discuss: New default recovery config settings

[Lionel Bouton <lionel+ceph-WTamNBQcZIx7tPAFqOLdPg@public.gmane.org>]

On 06/01/15 09:43, Jan Schermer wrote:
> We had to disable deep scrub or the cluster would me unusable - we need to turn it back on sooner or later, though.
> With minimal scrubbing and recovery settings, everything is mostly good. Turned out many issues we had were due to too few PGs - once we increased them from 4K to 16K everything sped up nicely (because the chunks are smaller), but during heavy activity we are still getting some “slow IOs”.
> I believe there is an ionice knob in newer versions (we still run Dumpling), and that should do the trick no matter how much additional “load” is put on the OSDs.
> Everybody’s bottleneck will be different - we run all flash so disk IO is not a problem but an OSD daemon is - no ionice setting will help with that, it just needs to be faster ;-)

If you are interested I'm currently testing a ruby script which
schedules the deep scrubs one at a time trying to simultaneously make
them fit in a given time window, avoid successive scrubs on the same OSD
and space the deep scrubs according to the amount of data scrubed.  I
use it because Ceph by itself can't prevent multiple scrubs to happen
simultaneously on the network and it can severely impact our VM performance.
I can clean it up and post it on Github.

Best regards,

Lionel
_______________________________________________
ceph-users mailing list
ceph-users@lists.ceph.com
http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com