I think smaller clusters get chocked up with the default backfill. I've seen latency on a four node cluster with 10 OSD each improve by setting osd_max_backfills to 2. I would try lowering it and see if it helps.
Also, if you are running both cluster and VM traffic on the same network, you could get congestion especially on a 1 Gb network.
Robert LeBlanc
On Fri, Dec 19, 2014 at 9:33 AM, Nico Schottelius <nico-ceph-users@xxxxxxxxxxxxxxx> wrote:
Hello,
another issue we have experienced with qemu VMs
(qemu 2.0.0) with ceph-0.80 on Ubuntu 14.04
managed by opennebula 4.10.1:
The VMs are completly frozen when rebalancing takes place,
they do not even respond to ping anymore.
Looking at the qemu processes they are in state "Sl".
Is this a known problem / have others seen this behaviour?
I have not yet tuned any backfilling parameters and it is a
cluster of 3 hosts with one host having 6 osds and two 1 one (so 8 osds
in total).
Our qemu runs with these rbd related options:
qemu-system-x86_64 ... -drive
file=rbd:one/one-38:id=libvirt:key=...:auth_supported=cephx\;none:mon_host=kaffee.private.ungleich.ch\;wein.private.ungleich.ch\;tee.private.ungleich.ch,if=none,id=drive-ide0-0-0,format=raw,cache=none
Cheers,
Nico
--
New PGP key: 659B 0D91 E86E 7E24 FD15 69D0 C729 21A1 293F 2D24
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