Hi,
We've observed very similar problems in our clusters, it requires a lot
of careful reweight to keep OSDs more or less at the same usage level.
Because of that issue, we're currently trying to keep Racks as regular
as possible. Hope the patch you mentioned will address this too.
Regards,
Bartek
On 11/22/2016 01:33 PM, Dan Van Der Ster wrote:
Hi,
I have a couple questions about http://tracker.ceph.com/issues/15653
In the ticket Sage discusses small/big drives, and the small drives get more data than expected.
But we observe this at the rack level: our cluster has four racks, with 7, 8, 8, 4 hosts respectively. The rack with 4 hosts is ~35% more full than the others.
So AFAICT, because of #15653, CRUSH does not currently work well if you try to build a pool which is replicated rack/host-wise when your rack/hosts are not all ~identical in size.
Are others noticing this pattern?
Or are we unusual in that our clusters are not flat/uniform in structure?
Cheers, Dan
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