They never fixed themselves? Did the reported times ever increase? If not I think that's just a reporting bug which is fixed in an unreleased branch, but I'd have to check the tracker to be sure. On Mon, Dec 8, 2014 at 8:23 PM, Christian Balzer <chibi@xxxxxxx> wrote: > > Hello, > > On Mon, 8 Dec 2014 19:51:00 -0800 Gregory Farnum wrote: > >> On Mon, Dec 8, 2014 at 6:39 PM, Christian Balzer <chibi@xxxxxxx> wrote: >> > >> > Hello, >> > >> > Debian Jessie cluster, thus kernel 3.16, ceph 0.80.7. >> > 3 storage nodes with 8 OSDs (journals on 4 SSDs) each, 3 mons. >> > 2 compute nodes, everything connected via Infiniband. >> > >> > This is pre-production, currently there are only 3 VMs and 2 of them >> > were idle at the time. The non-idle one was having 600GB of maildirs >> > copied onto it, which stresses things but not Ceph as those millions >> > of small files coalesce nicely and result in rather few Ceph ops. >> > >> > A couple of hours into that copy marathon (the source FS and machine >> > are slow and rsync isn't particular speedy with this kind of operation >> > either) this happened: >> > --- >> > 2014-12-06 19:20:57.023974 osd.23 10.0.8.23:6815/3552 77 : [WRN] slow >> > request 30 .673939 seconds old, received at 2014-12-06 >> > 19:20:26.346746: osd_op(client.33776 .0:743596 >> > rb.0.819b.238e1f29.00000003f52f [set-alloc-hint object_size 4194304 wr >> > ite_size 4194304,write 1748992~4096] 3.efa97e35 ack+ondisk+write e380) >> > v4 curren tly waiting for subops from 4,8 2014-12-06 19:20:57.023991 >> > osd.23 10.0.8.23:6815/3552 78 : [WRN] slow request 30 .673886 seconds >> > old, received at 2014-12-06 19:20:26.346799: >> > osd_op(client.33776 .0:743597 rb.0.819b.238e1f29.00000003f52f >> > [set-alloc-hint object_size 4194304 wr ite_size 4194304,write >> > 1945600~4096] 3.efa97e35 ack+ondisk+write e380) v4 curren tly waiting >> > for subops from 4,8 2014-12-06 19:20:57.323976 osd.1 >> > 10.0.8.21:6815/4868 123 : [WRN] slow request 30 .910821 seconds old, >> > received at 2014-12-06 19:20:26.413051: osd_op(client.33776 .0:743604 >> > rb.0.819b.238e1f29.00000003e628 [set-alloc-hint object_size 4194304 wr >> > ite_size 4194304,write 1794048~1835008] 3.5e76b8ba ack+ondisk+write >> > e380) v4 cur rently waiting for subops from 8,17 --- >> > >> > There were a few more later, but they all involved OSD 8 as common >> > factor. >> > >> > Alas there's nothing in the osd-8.log indicating why: >> > --- >> > 2014-12-06 19:13:13.933636 7fce85552700 0 -- 10.0.8.22:6835/5389 >> >> > 10.0.8.6:0/ 716350435 pipe(0x7fcec3c25900 sd=23 :6835 s=0 pgs=0 cs=0 >> > l=0 c=0x7fcebfad03c0).a ccept peer addr is really 10.0.8.6:0/716350435 >> > (socket is 10.0.8.6:50592/0) 2014-12-06 19:20:56.595773 7fceac82f700 >> > 0 log [WRN] : 3 slow requests, 3 included below; oldest blocked for > >> > 30.241397 secs 2014-12-06 19:20:56.595796 7fceac82f700 0 log [WRN] : >> > slow request 30.241397 seconds old, received at 2014-12-06 >> > 19:20:26.354247: osd_sub_op(client.33776.0:743596 3.235 >> > efa97e35/rb.0.819b.238e1f29.00000003f52f/head//3 [] v 380'3783 >> > snapset=0=[]:[] snapc=0=[]) v11 currently started 2014-12-06 >> > 19:20:56.595825 7fceac82f700 0 log [WRN] : slow request 30.240286 >> > seconds old, received at 2014-12-06 19:20:26.355358: >> > osd_sub_op(client.33776.0:743597 3.235 >> > efa97e35/rb.0.819b.238e1f29.00000003f52f/head//3 [] v 380'3784 >> > snapset=0=[]:[] snapc=0=[]) v11 currently started 2014-12-06 >> > 19:20:56.595837 7fceac82f700 0 log [WRN] : slow request 30.177186 >> > seconds old, received at 2014-12-06 19:20:26.418458: >> > osd_sub_op(client.33776.0:743604 3.ba >> > 5e76b8ba/rb.0.819b.238e1f29.00000003e628/head//3 [] v 380'6439 >> > snapset=0=[]:[] snapc=0=[]) v11 currently started ---- >> >> That these are started and nothing else suggests that they're probably >> waiting for one of the throttles to let them in, rather than >> themselves being particularly slow. >> > > If this was indeed caused by one of the (rather numerous) throttles, > wouldn't it be a good idea to log that fact? > A slow disk is one thing, Ceph permanently seizing up because something > exceeded a threshold sounds noteworthy to me. If it permanently seized up then this is not what happened; if the reporting just didn't go away then I'm not sure it's appropriate to log every time a throttle gets hit (some of them are supposed to or at least expected to be, since they keep the journal from running away from the backing store). > >> > >> > The HDDs and SSDs are new, there's nothing in the pertinent logs or >> > smart that indicates any problem with that HDD or its journal SSD, nor >> > the system in general. >> > This problem persisted (and the VM remained stuck) until OSD 8 was >> > restarted the next day when I discovered this. >> > >> > I suppose this is another "this can't/shouldn't happen" case, but I'd >> > be delighted about any suggestions as to what happened here, potential >> > prevention measures and any insights on how to maybe coax more >> > information out of Ceph if this happens again. >> >> Nah, there are a million reasons stuff can be slow. > This wasn't just slow. Those requests never completed even after half a > day had passed with the system and disks being basically idle. > >> It might just be a >> transient overload of the disk compared to the others. > > Transient would be fine (though highly unlikely in this scenario), however > it never recovered, see above. > > >> If you see this >> again while it's happening I'd check the perfcounters; if you're >> keeping historical checks of them go look at the blocked-up times and >> see if any of them are at or near their maximum values. >> -Gre >> > Ah, I should have thought of that before re-starting that OSD. > dump_historic_ops is at the default values, so that information is long gone. > > Regards, > > Christian > -- > Christian Balzer Network/Systems Engineer > chibi@xxxxxxx Global OnLine Japan/Fusion Communications > http://www.gol.com/ _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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