You can change some OSD tunables to lower the priority of backfills:
osd recovery max chunk: 8388608
osd recovery op priority: 2
In general a lower op priority means it will take longer for your
placement groups to go from degraded to active+clean, the idea is to
balance recovery time and not starving client requests. I've found 2
to work well on our clusters, YMMV.
On Mon, Oct 28, 2013 at 10:16 AM, Kevin Weiler
<Kevin.Weiler@xxxxxxxxxxxxxxx> wrote:
> Hi all,
>
> We have a ceph cluster that being used as a backing store for several VMs
> (windows and linux). We notice that when we reboot a node, the cluster
> enters a degraded state (which is expected), but when it begins to recover,
> it starts backfilling and it kills the performance of our VMs. The VMs run
> slow, or not at all, and also seem to switch it's ceph mounts to read-only.
> I was wondering 2 things:
>
> Shouldn't we be recovering instead of backfilling? It seems like backfilling
> is much more intensive operation
> Can we improve the recovery/backfill performance so that our VMs don't go
> down when there is a problem with the cluster?
>
>
> --
>
> Kevin Weiler
>
> IT
>
>
>
> IMC Financial Markets | 233 S. Wacker Drive, Suite 4300 | Chicago, IL 60606
> | http://imc-chicago.com/
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> Phone: +1 312-204-7439 | Fax: +1 312-244-3301 | E-Mail:
> kevin.weiler@xxxxxxxxxxxxxxx
>
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--
Kyle
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