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. > > > > 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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