I'm new to doing this all via systemd and systemd-coredump, but I appear to have gotten cores from two OSD processes. When xzipped they are < 2MIB each, but I threw them on my webserver to avoid polluting the mailing list. This seems oddly small, so if I've botched the process somehow let me know :)
https://aarontc.com/ceph/dumps/core.ceph-osd.150.082e9ca887c34cfbab183366a214a84c.6742.1492634493000000000000.xz https://aarontc.com/ceph/dumps/core.ceph-osd.150.082e9ca887c34cfbab183366a214a84c.7202.1492634508000000000000.xz And for reference: root@osd001:/var/lib/systemd/coredump# ceph -v ceph version 11.2.0 (f223e27eeb35991352ebc1f67423d4ebc252adb7) I am also investigating sysdig as recommended. Thanks! -Aaron On Mon, Apr 17, 2017 at 8:15 AM, Sage Weil <s...@newdream.net> wrote: > On Sat, 15 Apr 2017, Aaron Ten Clay wrote: > > Hi all, > > > > Our cluster is experiencing a very odd issue and I'm hoping for some > > guidance on troubleshooting steps and/or suggestions to mitigate the > issue. > > tl;dr: Individual ceph-osd processes try to allocate > 90GiB of RAM and > are > > eventually nuked by oom_killer. > > My guess is that there there is a bug in a decoding path and it's > trying to allocate some huge amount of memory. Can you try setting a > memory ulimit to something like 40gb and then enabling core dumps so you > can get a core? Something like > > ulimit -c unlimited > ulimit -m 20000000 > > or whatever the corresponding systemd unit file options are... > > Once we have a core file it will hopefully be clear who is > doing the bad allocation... > > sage > > > > > > > I'll try to explain the situation in detail: > > > > We have 24-4TB bluestore HDD OSDs, and 4-600GB SSD OSDs. The SSD OSDs > are in > > a different CRUSH "root", used as a cache tier for the main storage > pools, > > which are erasure coded and used for cephfs. The OSDs are spread across > two > > identical machines with 128GiB of RAM each, and there are three monitor > > nodes on different hardware. > > > > Several times we've encountered crippling bugs with previous Ceph > releases > > when we were on RC or betas, or using non-recommended configurations, so > in > > January we abandoned all previous Ceph usage, deployed LTS Ubuntu 16.04, > and > > went with stable Kraken 11.2.0 with the configuration mentioned above. > > Everything was fine until the end of March, when one day we find all but > a > > couple of OSDs are "down" inexplicably. Investigation reveals oom_killer > > came along and nuked almost all the ceph-osd processes. > > > > We've gone through a bunch of iterations of restarting the OSDs, trying > to > > bring them up one at a time gradually, all at once, various configuration > > settings to reduce cache size as suggested in this ticket: > > http://tracker.ceph.com/issues/18924... > > > > I don't know if that ticket really pertains to our situation or not, I > have > > no experience with memory allocation debugging. I'd be willing to try if > > someone can point me to a guide or walk me through the process. > > > > I've even tried, just to see if the situation was transitory, adding > over > > 300GiB of swap to both OSD machines. The OSD procs managed to allocate, > in a > > matter of 5-10 minutes, more than 300GiB of RAM pressure and became > > oom_killer victims once again. > > > > No software or hardware changes took place around the time this problem > > started, and no significant data changes occurred either. We added about > > 40GiB of ~1GiB files a week or so before the problem started and that's > the > > last time data was written. > > > > I can only assume we've found another crippling bug of some kind, this > level > > of memory usage is entirely unprecedented. What can we do? > > > > Thanks in advance for any suggestions. > > -Aaron > > > > > -- Aaron Ten Clay https://aarontc.com
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