Hi, I've recently seen some confusion over the number of PGs per pool versus per cluster on the mailing list. I also set too many PGs per pool b/c of this confusion.
IMO, it is fairly confusing to talk about PGs on the Pool page, but only vaguely talk about the number of PGs for the cluster. Here are some examples of confusing statements with suggested alternatives from the online docs: http://ceph.com/docs/master/rados/operations/pools/ "A typical configuration uses approximately 100 placement groups per OSD to provide optimal balancing without using up too many computing resources." -> "A typical configuration uses approximately 100 placement groups per OSD for all pools in the cluster to provide optimal balancing without using up too many computing resources." http://ceph.com/docs/master/rados/operations/placement-groups/ "It is mandatory to choose the value of pg_num because it cannot be calculated automatically. Here are a few values commonly used:" -> "It is mandatory to choose the value of pg_num. pg_num depends on the planned number of pools in the cluster. It cannot be determined automatically on pool creation. Please use this calculator: http://ceph.com/pgcalc/"; Thanks! C. _______________________________________________ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
