Hi Dan You can increase - not decrease .. I would go with 512 for this - that will allow you to increase in the future. from ceph.com "Having 512 or 4096 Placement Groups is roughly equivalent in a cluster with less than 50 OSDs " I don't even think you will be able to set pg num go 4096 - ceph will complain about too many pgs per osd. You can update pgs to a higher number, as I said, but also from ceph.com "However, increasing the PG Count of a pool is one of the most impactful events in a Ceph Cluster, and should be avoided for production clusters if possible. B On Tue, Apr 5, 2016 at 3:48 PM, <dan@xxxxxxxxxxxxxxxxx> wrote: > In a 12 OSD setup, the following config is there: > > (OSDs * 100) > Total PGs = ---------- > pool size > > > So with 12 OSD's and a pool size of 2 replicas, this would equal Total PGs > of 600 as per this url: > > http://docs.ceph.com/docs/master/rados/operations/placement-groups/#preselection > > Yet in the same page, at the top it says: > > Between 10 and 50 OSDs set pg_num to 4096 > > Our use is for shared hosting so there are lots of small writes and reads. > Which of these would be correct? > > Also is it a simple process to update PGs on a live system without affecting > service? > _______________________________________________ > 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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