On 03/06/2014 08:38 PM, Dan van der Ster wrote:
Hi all, We're about to go live with some qemu rate limiting to RBD, and I wanted to crosscheck our values with this list, in case someone can chime in with their experience or known best practices. The only reasonable, non test-suite, values I found on the web are: iops_wr 200 iops_rd 400 bps_wr 40000000 bps_rd 80000000 and those seem (to me) to offer a "pretty good" service level, with more iops than a typical disk yet lower throughput (which is good considering our single gigabit NICs on the hypervisors). Our main goal for the rate limiting is to protect the cluster from abusive users running fio, etc., while not overly restricting our varied legitimate applications. Any opinions here?
I normally only limit the writes since those are the most expensive in a Ceph cluster due to replication. With reads you can't really kill the disks since at some point all the objects will probably be in the page cache of the OSDs.
I don't see any good reason to limit reads, but if you do, I'd set it to something like 2.5k reads and 200MB/sec or so. Just to give the VM to boost with reads when needed.
You'll probably see that your cluster does a lot of writes and not so many reads.
Wido
Cheers, Dan _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
-- Wido den Hollander 42on B.V. Phone: +31 (0)20 700 9902 Skype: contact42on _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
