Thanks for the explanation that makes sense. Tim -----Original Message----- From: Tyler Brekke [mailto:tyler.brekke@xxxxxxxxxxx] Sent: Thursday, October 24, 2013 6:42 AM To: Snider, Tim Cc: ceph-users@xxxxxxxxxxxxxx Subject: Re: num of placement groups created for default pools Hey Tim, If you deployed with ceph-deploy then your monitors started without knowledge of how many OSDs you will be adding to your cluster. You can add 'osd_pool_default_pg_num' and 'osd_pool_default_pgp_num' to you ceph.conf before creating your monitors to have the default pools created with the proper number of placement groups. I believe with the old mkcephfs script the number of osds was used to give a better default pg count. I don't think this is really necessary anymore as you can increase your placement group size now. ceph osd pool set <poolname> pg_num <num> ceph osd pool set <poolname> pgp_num <num> On Wed, Oct 23, 2013 at 6:13 AM, Snider, Tim <Tim.Snider@xxxxxxxxxx> wrote: > I have a newly created cluster with 68 osds and the default of 2 replicas. The default pools are created with 64 placement groups . The documentation in http://ceph.com/docs/master/rados/operations/pools/ states for osd pool creation : > "We recommend approximately 50-100 placement groups per OSD to balance out memory and CPU requirements and per-OSD load. For a single pool of objects, you can use the following formula: Total PGS = (osds *100)/Replicas" > > For this cluster pools should have 3200 pgs [ (64*100)/2] according to the recommendation. > Why isn't the guideline followed for default pools? > Maybe they're created prior to having all the osds activated? > Maybe I'm reading the documentation incorrectly. > > /home/ceph/bin# ceph osd getmaxosd > max_osd = 68 in epoch 219 > /home/ceph/bin# ceph osd getmaxosd > max_osd = 68 in epoch 219 > /home/ceph/bin# ceph osd lspools > 0 data,1 metadata,2 rbd, > /home/ceph/bin# ceph osd pool get data pg_num > pg_num: 64 > /home/ceph/bin# ceph osd pool get data size > size: 2 > > Thanks, > Tim > _______________________________________________ > 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
 |