On 10/19/18 7:51 AM, xiang.dai@xxxxxxxxxxx wrote: > Hi! > > I use ceph 13.2.1 (5533ecdc0fda920179d7ad84e0aa65a127b20d77) mimic > (stable), and find that: > > When expand whole cluster, i update pg_num, all succeed, but the status > is as below: > cluster: > id: 41ef913c-2351-4794-b9ac-dd340e3fbc75 > health: HEALTH_WARN > 3 pools have pg_num > pgp_num > > Then i update pgp_num too, warning miss. > > What makes me confused is that when i create whole cluster at first time, > i use "ceph osd create pool pool_name pg_num", the pgp_num is auto equal > to pg_num. > > But "ceph osd set pool pool_name pg_num" not. > > Why does this design? > > Why do not auto update pgp_num when update pg_num? > Because when changing pg_num only the Placement Groups are created, data isn't moving yet. pgp_num, Placement Groups for Placement influences how CRUSH works. When you change that value data actually starts to move. pgp_num can never be larger then pg_num though. Some people choose to increase pgp_num in small steps so that the data migration isn't massive. Wido > Thanks > > _______________________________________________ > 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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