On Tue, Nov 4, 2014 at 10:49 PM, Udo Lembke <ulembke@xxxxxxxxxxxx> wrote: > Hi, > since a long time I'm looking for performance improvements for our > ceph-cluster. > The last expansion got better performance, because we add another node > (with 12 OSDs). The storage utilization was after that 60%. > > Now we reach again 69% (the next nodes are waiting for installation) and > the performance drop! OK, we also change the ceph-version from 0.72.x to > firefly. > But I'm wonder if there an relationship between utilization an performance?! > The OSDs are xfs disks, but now i start to use ext4, because of the bad > fragmentation on a xfs-filesystem (yes, I use the mountoption > allocsize=4M allready). > > Has anybody the same effect? > > Udo > AFAIR there is a specific point somewhere in Ceph user guide to not reach commit ratio higher than 70% due to heavy performance impact. In practice, hot storage feels even fifty-percent commit on a xfs with default mount parameters, so you may consider as a rule of thumb to reach commit not higher than 60 percents. For mixed or cold storage numbers will vary, as average clat and write throughput will matter less. > _______________________________________________ > ceph-users mailing list > ceph-users@xxxxxxxxxxxxxx > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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