On Wed, 1 Jun 2016, Yan, Zheng wrote:
> On Wed, Jun 1, 2016 at 6:15 AM, James Webb <jamesw@xxxxxxxxxxx> wrote:
> > Dear ceph-users...
> >
> > My team runs an internal buildfarm using ceph as a backend storage platform. We’ve recently upgraded to Jewel and are having reliability issues that we need some help with.
> >
> > Our infrastructure is the following:
> > - We use CEPH/CEPHFS (10.2.1)
> > - We have 3 mons and 6 storage servers with a total of 36 OSDs (~4160 PGs).
> > - We use enterprise SSDs for everything including journals
> > - We have one main mds and one standby mds.
> > - We are using ceph kernel client to mount cephfs.
> > - We have upgrade to Ubuntu 16.04 (4.4.0-22-generic kernel)
> > - We are using a kernel NFS to serve NFS clients from a ceph mount (~ 32 nfs threads. 0 swappiness)
> > - These are physical machines with 8 cores & 32GB memory
> >
> > On a regular basis, we lose all IO via ceph FS. We’re still trying to isolate the issue but it surfaces as an issue between MDS and ceph client.
> > We can’t tell if our our NFS server is overwhelming the MDS or if this is some unrelated issue. Tuning NFS server has not solved our issues.
> > So far our only recovery has been to fail the MDS and then restart our NFS. Any help or advice will be appreciated on the CEPH side of things.
> > I’m pretty sure we’re running with default tuning of CEPH MDS configuration parameters.
> >
> >
> > Here are the relevant log entries.
> >
> > From my primary MDS server, I start seeing these entries start to pile up:
> >
> > 2016-05-31 14:34:07.091117 7f9f2eb87700 0 log_channel(cluster) log [WRN] : client.4283066 isn't responding to mclientcaps(revoke), ino 10000004491 pending pAsLsXsFsxcrwb issued pAsxLsXsxFsxcrwb, sent 63.877480 seconds ago\
> > 2016-05-31 14:34:07.091129 7f9f2eb87700 0 log_channel(cluster) log [WRN] : client.4283066 isn't responding to mclientcaps(revoke), ino 10000005ddf pending pAsLsXsFsxcrwb issued pAsxLsXsxFsxcrwb, sent 63.877382 seconds ago\
> > 2016-05-31 14:34:07.091133 7f9f2eb87700 0 log_channel(cluster) log [WRN] : client.4283066 isn't responding to mclientcaps(revoke), ino 10000000a2a pending pAsLsXsFsxcrwb issued pAsxLsXsxFsxcrwb, sent 63.877356 seconds ago
> >
> > From my NFS server, I see these entries from dmesg also start piling up:
> > [Tue May 31 14:33:09 2016] libceph: skipping mds0 X.X.X.195:6800 seq 0 expected 4294967296
> > [Tue May 31 14:33:09 2016] libceph: skipping mds0 X.X.X.195:6800 seq 1 expected 4294967296
> > [Tue May 31 14:33:09 2016] libceph: skipping mds0 X.X.X.195:6800 seq 2 expected 4294967296
> >
>
> 4294967296 is 0x100000000, this looks like sequence overflow.
>
> In src/msg/Message.h:
>
> class Message {
> ...
> unsigned get_seq() const { return header.seq; }
> void set_seq(unsigned s) { header.seq = s; }
> ...
> }
>
> in src/msg/simple/Pipe.cc
>
> class Pipe {
> ...
> __u32 get_out_seq() { return out_seq; }
> ...
> }
>
> Is this bug or intentional ?
That's a bug. The seq values are intended to be 32 bits.
(We should also be using the ceph_cmp_seq (IIRC) helper for any inequality
checks, which does a sloppy comparison so that a 31-bit signed difference
is used to determine > or <. It sounds like in this case we're just
failing an equality check, though.)
sage
> Regards
> Yan, Zheng
>
>
> > Next, we find something like this on one of the OSDs.:
> > 2016-05-31 14:34:44.130279 mon.0 XX.XX.XX.188:6789/0 1272184 : cluster [INF] HEALTH_WARN; mds0: Client storage-nfs-01 failing to respond to capability release
> >
> > Finally, I am seeing consistent HEALTH_WARN in my status regarding trimming which I am not sure if it is related:
> >
> > cluster XXXXXXXX-bd8f-4091-bed3-8586fd0d6b46
> > health HEALTH_WARN
> > mds0: Behind on trimming (67/30)
> > monmap e3: 3 mons at {storage02=X.X.X.190:6789/0,storage03=X.X.X.189:6789/0,storage04=X.X.X.188:6789/0}
> > election epoch 206, quorum 0,1,2 storage04,storage03,storage02
> > fsmap e74879: 1/1/1 up {0=cephfs-03=up:active}, 1 up:standby
> > osdmap e65516: 36 osds: 36 up, 36 in
> > pgmap v15435732: 4160 pgs, 3 pools, 37539 GB data, 9611 kobjects
> > 75117 GB used, 53591 GB / 125 TB avail
> > 4160 active+clean
> > client io 334 MB/s rd, 319 MB/s wr, 5839 op/s rd, 4848 op/s wr
> >
> >
> > Regards,
> > James Webb
> > DevOps Engineer, Engineering Tools
> > Unity Technologies
> > _______________________________________________
> > ceph-users mailing list
> > ceph-users@xxxxxxxxxxxxxx
> > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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