On Wed, Mar 11, 2015 at 3:49 PM, Francois Lafont <flafdivers@xxxxxxx> wrote: > Hi, > > I was always in the same situation: I couldn't remove an OSD without > have some PGs definitely stuck to the "active+remapped" state. > > But I remembered I read on IRC that, before to mark out an OSD, it > could be sometimes a good idea to reweight it to 0. So, instead of > doing [1]: > > ceph osd out 3 > > I have tried [2]: > > ceph osd crush reweight osd.3 0 # waiting for the rebalancing... > ceph osd out 3 > > and it worked. Then I could remove my osd with the online documentation: > http://ceph.com/docs/master/rados/operations/add-or-rm-osds/#removing-osds-manual > > Now, the osd is removed and my cluster is HEALTH_OK. \o/ > > Now, my question is: why my cluster was definitely stuck to "active+remapped" > with [1] but was not with [2]? Personally, I have absolutely no explanation. > If you have an explanation, I'd love to know it. If I remember/guess correctly, if you mark an OSD out it won't necessarily change the weight of the bucket above it (ie, the host), whereas if you change the weight of the OSD then the host bucket's weight changes. That makes for different mappings, and since you only have a couple of OSDs per host (normally: hurray!) and not many hosts (normally: sadness) then marking one OSD out makes things harder for the CRUSH algorithm. -Greg > > Should the "reweight" command be present in the online documentation? > http://ceph.com/docs/master/rados/operations/add-or-rm-osds/#removing-osds-manual > If yes, I can make a pull request on the doc with pleasure. ;) > > Regards. > > -- > François Lafont > _______________________________________________ > 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
 |