Hi Janne: Thanks for your response. Approximately 100 PGs per OSD, yes, I missed out this part. I am still a little confused. Because 100-PGs-per-OSD rule is the result of sumation of all used pools . I konw I can create many pools.Assume that I have 5 pools now , and the rule has already been met. So if I create the sixth pool, the total PGs will increased , then the PGs per OSD will be more then 100. Will this not violate the rule ? On Fri, Mar 9, 2018 at 5:40 PM, Janne Johansson <icepic.dz@xxxxxxxxx> wrote: > > > 2018-03-09 10:27 GMT+01:00 Will Zhao <zhao6305@xxxxxxxxx>: >> >> Hi all: >> >> I have a tiny question. I have read the documents, and it >> recommend approximately 100 placement groups for normal usage. > > > Per OSD. Approximately 100 PGs per OSD, when all used pools are summed up. > For things like radosgw, let it use the low defaults (8?) and then expand on > the pools > that actually see a lot of data getting into them, leave the rest as is. > > >> >> Because the pg num can not be decreased, so if in current cluster, >> the pg num have met this rule, and when I try to create a new pool , >> what pg num I should set ? I think no matter what I do , it will >> violate the pg-num-rule, add burden to osd. This means , if I want my >> cluster be used by many different users, I should bulid a new cluster >> for new user ? >> > > No, one cluster can serve a lot of clients. You can have lots of pools if > you need, > and those pools can have separate OSD hosts serving them if you need strong > separation, but still managed from the same cluster. > > -- > May the most significant bit of your life be positive. _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com