maybe, - use the top program to look at a threaded listing of the ceph-mds process and see which thread(s) are consuming the most cpu - use gstack to attach to the ceph-mds process and dump the backtrace into a file; we can then map the thread with highest cpu consumption to the gstack output - enable debug logs (level 20) for the ceph-mds process for a few seconds and look at what's happening in there or share the logs with the team here But I wonder if you could do this on your production system. On Mon, Nov 7, 2022 at 4:34 PM Olli Rajala <olli.rajala@xxxxxxxx> wrote: > I might have spoken too soon :( > > Now about 60h after dropping the caches the write bandwidth has gone up > linearly from those initial hundreds of kB/s to now nearly 10MB/s. > > I don't think this could be caused by the cache just filling up again > either. After dropping the cache I tested if filling up the cache would > show any bw increase by running "tree" at the root of one of the mounts and > it didn't affect anything at the time. So basically the cache has been > fully saturated all this time now. > > Boggled, > --------------------------- > Olli Rajala - Lead TD > Anima Vitae Ltd. > www.anima.fi > --------------------------- > > > On Sat, Nov 5, 2022 at 12:47 PM Olli Rajala <olli.rajala@xxxxxxxx> wrote: > > > Oh Lordy, > > > > Seems like I finally got this resolved. And all it needed in the end was > > to drop the mds caches with: > > ceph tell mds.`hostname` cache drop > > > > The funny thing is that whatever the issue with the cache was it had > > persisted through several Ceph upgrades and node reboots. It's been a > live > > production system so I guess that there just never has been a moment > where > > all mds would have been down and thus make it fully rebuild the cache... > > maybe :| > > > > Unfortunately I don't remember when this issue arose and my metrics don't > > reach far back enough... but I wonder if this could have started already > > when I did Octopus->Pacific upgrade... > > > > Cheers, > > --------------------------- > > Olli Rajala - Lead TD > > Anima Vitae Ltd. > > www.anima.fi > > --------------------------- > > > > > > On Mon, Oct 24, 2022 at 9:36 PM Olli Rajala <olli.rajala@xxxxxxxx> > wrote: > > > >> I tried my luck and upgraded to 17.2.4 but unfortunately that didn't > make > >> any difference here either. > >> > >> I also looked more again at all kinds of client op and request stats and > >> wotnot which only made me even more certain that this io is not caused > by > >> any clients. > >> > >> What internal mds operation or mechanism could cause such high idle > write > >> io? I've tried to fiddle a bit with some of the mds cache trim and > memory > >> settings but I haven't noticed any effect there. Any pointers > appreciated. > >> > >> Cheers, > >> --------------------------- > >> Olli Rajala - Lead TD > >> Anima Vitae Ltd. > >> www.anima.fi > >> --------------------------- > >> > >> > >> On Mon, Oct 17, 2022 at 10:28 AM Olli Rajala <olli.rajala@xxxxxxxx> > >> wrote: > >> > >>> Hi Patrick, > >>> > >>> With "objecter_ops" did you mean "ceph tell mds.pve-core-1 ops" and/or > >>> "ceph tell mds.pve-core-1 objecter_requests"? Both these show very few > >>> requests/ops - many times just returning empty lists. I'm pretty sure > that > >>> this I/O isn't generated by any clients - I've earlier tried to isolate > >>> this by shutting down all cephfs clients and this didn't have any > >>> noticeable effect. > >>> > >>> I tried to watch what is going on with that "perf dump" but to be > honest > >>> all I can see is some numbers going up in the different sections :) > >>> ...don't have a clue what to focus on and how to interpret that. > >>> > >>> Here's a perf dump if you or anyone could make something out of that: > >>> https://gist.github.com/olliRJL/43c10173aafd82be22c080a9cd28e673 > >>> > >>> Tnx! > >>> o. > >>> > >>> --------------------------- > >>> Olli Rajala - Lead TD > >>> Anima Vitae Ltd. > >>> www.anima.fi > >>> --------------------------- > >>> > >>> > >>> On Fri, Oct 14, 2022 at 8:32 PM Patrick Donnelly <pdonnell@xxxxxxxxxx> > >>> wrote: > >>> > >>>> Hello Olli, > >>>> > >>>> On Thu, Oct 13, 2022 at 5:01 AM Olli Rajala <olli.rajala@xxxxxxxx> > >>>> wrote: > >>>> > > >>>> > Hi, > >>>> > > >>>> > I'm seeing constant 25-50MB/s writes to the metadata pool even when > >>>> all > >>>> > clients and the cluster is idling and in clean state. This surely > >>>> can't be > >>>> > normal? > >>>> > > >>>> > There's no apparent issues with the performance of the cluster but > >>>> this > >>>> > write rate seems excessive and I don't know where to look for the > >>>> culprit. > >>>> > > >>>> > The setup is Ceph 16.2.9 running in hyperconverged 3 node core > >>>> cluster and > >>>> > 6 hdd osd nodes. > >>>> > > >>>> > Here's typical status when pretty much all clients are idling. Most > >>>> of that > >>>> > write bandwidth and maybe fifth of the write iops is hitting the > >>>> > metadata pool. > >>>> > > >>>> > > >>>> > --------------------------------------------------------------------------------------------------- > >>>> > root@pve-core-1:~# ceph -s > >>>> > cluster: > >>>> > id: 2088b4b1-8de1-44d4-956e-aa3d3afff77f > >>>> > health: HEALTH_OK > >>>> > > >>>> > services: > >>>> > mon: 3 daemons, quorum pve-core-1,pve-core-2,pve-core-3 (age 2w) > >>>> > mgr: pve-core-1(active, since 4w), standbys: pve-core-2, > >>>> pve-core-3 > >>>> > mds: 1/1 daemons up, 2 standby > >>>> > osd: 48 osds: 48 up (since 5h), 48 in (since 4M) > >>>> > > >>>> > data: > >>>> > volumes: 1/1 healthy > >>>> > pools: 10 pools, 625 pgs > >>>> > objects: 70.06M objects, 46 TiB > >>>> > usage: 95 TiB used, 182 TiB / 278 TiB avail > >>>> > pgs: 625 active+clean > >>>> > > >>>> > io: > >>>> > client: 45 KiB/s rd, 38 MiB/s wr, 6 op/s rd, 287 op/s wr > >>>> > > >>>> > --------------------------------------------------------------------------------------------------- > >>>> > > >>>> > Here's some daemonperf dump: > >>>> > > >>>> > > >>>> > --------------------------------------------------------------------------------------------------- > >>>> > root@pve-core-1:~# ceph daemonperf mds.`hostname -s` > >>>> > > >>>> > ----------------------------------------mds----------------------------------------- > >>>> > --mds_cache--- ------mds_log------ -mds_mem- > -------mds_server------- > >>>> mds_ > >>>> > -----objecter------ purg > >>>> > req rlat fwd inos caps exi imi hifc crev cgra ctru cfsa cfa hcc > >>>> hccd > >>>> > hccr prcr|stry recy recd|subm evts segs repl|ino dn |hcr hcs hsr > >>>> cre > >>>> > cat |sess|actv rd wr rdwr|purg| > >>>> > 40 0 0 767k 78k 0 0 0 1 6 1 0 0 5 > >>>> 5 > >>>> > 3 7 |1.1k 0 0 | 17 3.7k 134 0 |767k 767k| 40 5 0 > >>>> 0 > >>>> > 0 |110 | 4 2 21 0 | 2 > >>>> > 57 2 0 767k 78k 0 0 0 3 16 3 0 0 11 > >>>> 11 > >>>> > 0 17 |1.1k 0 0 | 45 3.7k 137 0 |767k 767k| 57 8 0 > >>>> 0 > >>>> > 0 |110 | 0 2 28 0 | 4 > >>>> > 57 4 0 767k 78k 0 0 0 4 34 4 0 0 34 > >>>> 33 > >>>> > 2 26 |1.0k 0 0 |134 3.9k 139 0 |767k 767k| 57 13 0 > >>>> 0 > >>>> > 0 |110 | 0 2 112 0 | 19 > >>>> > 67 3 0 767k 78k 0 0 0 6 32 6 0 0 22 > >>>> 22 > >>>> > 0 32 |1.1k 0 0 | 78 3.9k 141 0 |767k 768k| 67 4 0 > >>>> 0 > >>>> > 0 |110 | 0 2 56 0 | 2 > >>>> > > >>>> > --------------------------------------------------------------------------------------------------- > >>>> > Any ideas where to look at? > >>>> > >>>> Check the perf dump output of the mds: > >>>> > >>>> ceph tell mds.<fs_name>:0 perf dump > >>>> > >>>> over a period of time to identify what's going on. You can also look > >>>> at the objecter_ops (another tell command) for the MDS. > >>>> > >>>> -- > >>>> Patrick Donnelly, Ph.D. > >>>> He / Him / His > >>>> Principal Software Engineer > >>>> Red Hat, Inc. > >>>> GPG: 19F28A586F808C2402351B93C3301A3E258DD79D > >>>> > >>>> > _______________________________________________ > ceph-users mailing list -- ceph-users@xxxxxxx > To unsubscribe send an email to ceph-users-leave@xxxxxxx > > -- Milind _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx
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