What you want to do is to stop the OSD (and all its copies of data it contains) by stopping the OSD service immediately. The downside of this approach is it causes the PGs on that OSD to be degraded. But the upside is the OSD which has bad hardware is immediately no longer participating in any client IO (the source of your RGW 503s). In this situation the PGs go into degraded+backfilling
The alternative method is to keep the failing OSD up and in the cluster but slowly migrate the data off of it, this would be a long drawn out period of time in which the failing disk would continue to serve client reads and also facilitate backfill but you wouldnt take a copy of the data out of the cluster and cause degraded PGs. In this scenario the PGs would be remapped+backfilling I tried to find a way to have your cake and eat it to in relation to this "predicament" in this tracker issue: https://tracker.ceph.com/issues/44400 but it was deemed "wont fix". Respectfully, *Wes Dillingham* LinkedIn <http://www.linkedin.com/in/wesleydillingham> w...@wesdillingham.com On Fri, Apr 26, 2024 at 11:25 AM Mary Zhang <maryzhang0...@gmail.com> wrote: > Thank you Eugen for your warm help! > > I'm trying to understand the difference between 2 methods. > For method 1, or "ceph orch osd rm osd_id", OSD Service — Ceph > Documentation > <https://docs.ceph.com/en/latest/cephadm/services/osd/#remove-an-osd> says > it involves 2 steps: > > 1. > > evacuating all placement groups (PGs) from the OSD > 2. > > removing the PG-free OSD from the cluster > > For method 2, or the procedure you recommended, Adding/Removing OSDs — Ceph > Documentation > < > https://docs.ceph.com/en/latest/rados/operations/add-or-rm-osds/#removing-osds-manual > > > says > "After the OSD has been taken out of the cluster, Ceph begins rebalancing > the cluster by migrating placement groups out of the OSD that was removed. > " > > What's the difference between "evacuating PGs" in method 1 and "migrating > PGs" in method 2? I think method 1 must read the OSD to be removed. > Otherwise, we would not see slow ops warning. Does method 2 not involve > reading this OSD? > > Thanks, > Mary > > On Fri, Apr 26, 2024 at 5:15 AM Eugen Block <ebl...@nde.ag> wrote: > > > Hi, > > > > if you remove the OSD this way, it will be drained. Which means that > > it will try to recover PGs from this OSD, and in case of hardware > > failure it might lead to slow requests. It might make sense to > > forcefully remove the OSD without draining: > > > > - stop the osd daemon > > - mark it as out > > - osd purge <id|osd.id> [--force] [--yes-i-really-mean-it] > > > > Regards, > > Eugen > > > > Zitat von Mary Zhang <maryzhang0...@gmail.com>: > > > > > Hi, > > > > > > We recently removed an osd from our Cepth cluster. Its underlying disk > > has > > > a hardware issue. > > > > > > We use command: ceph orch osd rm osd_id --zap > > > > > > During the process, sometimes ceph cluster enters warning state with > slow > > > ops on this osd. Our rgw also failed to respond to requests and > returned > > > 503. > > > > > > We restarted rgw daemon to make it work again. But the same failure > > occured > > > from time to time. Eventually we noticed that rgw 503 error is a result > > of > > > osd slow ops. > > > > > > Our cluster has 18 hosts and 210 OSDs. We expect remove an osd with > > > hardware issue won't impact cluster performance & rgw availbility. Is > our > > > expectation reasonable? What's the best way to handle osd with hardware > > > failures? > > > > > > Thank you in advance for any comments or suggestions. > > > > > > Best Regards, > > > Mary Zhang > > > _______________________________________________ > > > ceph-users mailing list -- ceph-users@ceph.io > > > To unsubscribe send an email to ceph-users-le...@ceph.io > > > > > > _______________________________________________ > > ceph-users mailing list -- ceph-users@ceph.io > > To unsubscribe send an email to ceph-users-le...@ceph.io > > > _______________________________________________ > ceph-users mailing list -- ceph-users@ceph.io > To unsubscribe send an email to ceph-users-le...@ceph.io > _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-le...@ceph.io
