On 2015-01-01 08:27, Dyweni - Ceph-Users wrote:
Hi, I'm going to take a stab at this, since I've just recently/am
currently
dealing with this/something similar myself.
On 2014-12-31 21:59, Lindsay Mathieson wrote:
As mentioned before :) we have two osd ndoes with one 3TB osd each.
(replica
2)
About to add a smaller (1TB) faster drive to each node
From the docs, normal practice would be to weight it in accordance
with size,
i.e 3 for the 3TB OSD, 1 for the 1TB OSD.
But I'd like to spread it 50/50 to take better advantage of the faster
drive,
so weight them all at 1. Bad idea?
As long as your total data used (ceph df) / # of osds < your smallest
drive
capacity, you should be fine.
I suspect a better configuration would be to leave your weights alone
and to
change your primary affinity so that the osd with the ssd is used
first. You
might a little improvement on the writes (since the spinners have to
work too),
but the reads should have the most improvement (since ceph only has to
read
from the ssd).
http://ceph.com/docs/master/rados/operations/crush-map/#primary-affinity
This may help you too:
http://cephnotes.ksperis.com/blog/2014/08/20/ceph-primary-affinity
We only have 1TB of data so I'm presuming the 1TB drives would get
500GB each.
--
Lindsay
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