Am 23.02.2018 um 01:05 schrieb Gregory Farnum: > > > On Wed, Feb 21, 2018 at 2:46 PM Oliver Freyermuth > <freyerm...@physik.uni-bonn.de <mailto:freyerm...@physik.uni-bonn.de>> wrote: > > Dear Cephalopodians, > > in a Luminous 12.2.3 cluster with a pool with: > - 192 Bluestore OSDs total > - 6 hosts (32 OSDs per host) > - 2048 total PGs > - EC profile k=4, m=2 > - CRUSH failure domain = host > which results in 2048*6/192 = 64 PGs per OSD on average, I run into > issues with PG overdose protection. > > In case I reinstall one OSD host (zapping all disks), and recreate the > OSDs one by one with ceph-volume, > they will usually come back "slowly", i.e. one after the other. > > This means the first OSD will initially be assigned all 2048 PGs (to > fulfill the "failure domain host" requirement), > thus breaking through the default osd_max_pg_per_osd_hard_ratio of 2. > We also use mon_max_pg_per_osd default, i.e. 200. > > This appears to cause the previously active (but of course > undersized+degraded) PGs to enter an "activating+remapped" state, > and hence they become unavailable. > Thus, data availability is reduced. All this is caused by adding an OSD! > > Of course, as more and more OSDs are added until all 32 are back online, > this situation is relaxed. > Still, I observe that some PGs get stuck in this "activating" state, and > can't seem to figure out from logs or by dumping them > what's the actual reason. Waiting does not help, PGs stay "activating", > data stays inaccessible. > > > Can you upload logs from each of the OSDs that are (and should be, but > aren't) involved with one of the PGs that happens to? (ceph-post-file) And > create a ticket about it?
I'll reproduce in the weekend and then capture the logs, at least I did not see anything in there, but I also am not yet too much used to reading them. What I can already confirm for sure is that after I set: osd_max_pg_per_osd_hard_ratio = 32 in ceph.conf (global) and deploy new OSD hosts with that, the problem has fully vanished. I have already tested this with two machines. Cheers, Oliver > > Once you have a good map, all the PGs should definitely activate themselves. > -Greg > > > Waiting a bit and manually restarting the ceph-OSD-services on the > reinstalled host seems to bring them back. > Also, adjusting osd_max_pg_per_osd_hard_ratio to something large (e.g. > 10) appears to prevent the issue. > > So my best guess is that this is related to PG overdose protection. > Any ideas on how to best overcome this / similar observations? > > It would be nice to be able to reinstall an OSD host without temporarily > making data unavailable, > right now the only thing which comes to my mind is to effectively disable > PG overdose protection. > > Cheers, > Oliver > > _______________________________________________ > ceph-users mailing list > firstname.lastname@example.org <mailto:email@example.com> > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >
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