Thank you Frank, "degradation is exactly what needs to be avoided/fixed at all cost", clear and loud, point is taken! I didn't actually quite get it last time. I used to think degradation would be OK, but now, I agree with you, that is not OK at all for production storage. Appreciate your patience! Tony > -----Original Message----- > From: Frank Schilder <frans@xxxxxx> > Sent: Tuesday, February 2, 2021 11:47 PM > To: Tony Liu <tonyliu0592@xxxxxxxxxxx>; ceph-users@xxxxxxx > Subject: Re: replace OSD without PG remapping > > You asked about exactly this before: > https://lists.ceph.io/hyperkitty/list/ceph- > users@xxxxxxx/thread/IGYCYJTAMBDDOD2AQUCJQ6VSUWIO4ELW/#ZJU3555Z5WQTJDPCT > MPZ6LOFTIUKKQUS > > It is not possible to avoid remapping, because if the PGs are not > remapped you would have degraded redundancy. In any storage system, this > degradation is exactly what needs to be avoided/fixed at all cost. > > I don't see an issue with health status messages issued by self-healing. > That's the whole point of ceph, just let it do its job and don't get > freaked out by health_warn. > > You can, however try to keep the window of rebalancing short and this is > exactly what was discussed in the thread above already. As is pointed > out there as well, even this is close to pointless. Just deploy a few > more disks than you need, let the broken ones go and be happy that ceph > is taking care of the rest and even tells you about its progress. > > Best regards, > ================= > Frank Schilder > AIT Risø Campus > Bygning 109, rum S14 > > ________________________________________ > From: Tony Liu <tonyliu0592@xxxxxxxxxxx> > Sent: 03 February 2021 03:10:26 > To: ceph-users@xxxxxxx > Subject: replace OSD without PG remapping > > Hi, > > There are multiple different procedures to replace an OSD. > What I want is to replace an OSD without PG remapping. > > #1 > I tried "orch osd rm --replace", which sets OSD reweight 0 and status > "destroyed". "orch osd rm status" shows "draining". > All PGs on this OSD are remapped. Checked "pg dump", can't find this OSD > any more. > > 1) Given [1], setting weight 0 seems better than setting reweight 0. > Is that right? If yes, should we change the behavior of "orch osd rm -- > replace"? > > 2) "ceph status" doesn't show anything about OSD draining. > Is there any way to see the progress of draining? > Is there actually copy happening? The PG on this OSD is remapped and > copied to another OSD, right? > > 3) When OSD is replaced, there will be remapping and backfilling. > > 4) There is remapping in #2 and remapping again in #3. > I want to avoid it. > > #2 > Is there any procedure that doesn't mark OSD out (set reweight 0), > neither set weight 0, which should keep PG map unchanged, but just warn > about less redundancy (one out of 3 OSDs of PG is down), and when OSD is > replaced, no remapping, just data backfilling? > > [1] https://ceph.com/geen-categorie/difference-between-ceph-osd- > reweight-and-ceph-osd-crush-reweight/ > > > Thanks! > Tony > _______________________________________________ > ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an > email to ceph-users-leave@xxxxxxx _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx
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