Hello *,
we have an issue with a Luminous cluster (all 12.2.5, except one on
12.2.7) for RBD (OpenStack) and CephFS. This is the osd tree:
host1:~ # ceph osd tree
ID CLASS WEIGHT TYPE NAME STATUS REWEIGHT PRI-AFF
-1 22.57602 root default
-4 1.81998 host host5
14 hdd 0.90999 osd.14 up 0.84999 0.50000
15 hdd 0.90999 osd.15 up 0.84999 0.50000
-2 6.27341 host host1
1 hdd 0.92429 osd.1 up 1.00000 1.00000
4 hdd 0.92429 osd.4 up 1.00000 1.00000
6 hdd 0.92429 osd.6 up 1.00000 1.00000
13 hdd 0.92429 osd.13 up 1.00000 1.00000
16 hdd 0.92429 osd.16 up 1.00000 1.00000
18 hdd 0.92429 osd.18 up 1.00000 1.00000
10 ssd 0.72769 osd.10 up 1.00000 1.00000
-3 6.27341 host host2
2 hdd 0.92429 osd.2 up 1.00000 1.00000
5 hdd 0.92429 osd.5 up 1.00000 1.00000
7 hdd 0.92429 osd.7 up 1.00000 1.00000
12 hdd 0.92429 osd.12 up 1.00000 1.00000
17 hdd 0.92429 osd.17 up 1.00000 1.00000
19 hdd 0.92429 osd.19 up 1.00000 1.00000
9 ssd 0.72769 osd.9 up 1.00000 1.00000
-5 4.57043 host host3
0 hdd 0.92429 osd.0 up 1.00000 1.00000
3 hdd 0.92429 osd.3 up 1.00000 1.00000
8 hdd 0.92429 osd.8 up 1.00000 1.00000
11 hdd 0.92429 osd.11 up 1.00000 1.00000
20 ssd 0.87329 osd.20 up 1.00000 0
-16 3.63879 host host4
21 hdd 0.90970 osd.21 up 1.00000 0
22 hdd 0.90970 osd.22 up 1.00000 0
23 hdd 0.90970 osd.23 up 1.00000 0
24 hdd 0.90970 osd.24 up 1.00000 0
A couple of weeks ago a new host was added to the cluster (host4),
containing four bluestore OSDs (HDD) with block.db on LVM (SSD). All
went well and the cluster was in HEALTH_OK state for some time.
Then suddenly we experienced flapping OSDs, first on host3 (MON, MGR,
OSD) for a single OSD (OSD.20 on SSD). Later host4 (OSD only) started
flapping, too, this time all four OSDs (OSD.21 - OSD.24) were
affected. Only two reboots brought the node back up.
We found segfaults from safe_timer and were pretty sure that the
cluster was hit by [1], it all sounded very much like our experience.
That's why we started to upgrade the new host to 12.2.7, we waited
before upgrading the other nodes in case some other issues would come
up. Two days later the same host was flapping again, but without a
segfault or any other trace of the cause. We started to assume that
the segfault could be a result of the segfault, not the cause.
Since it seems impossible to predict that flapping we don't have debug
logs for those OSDs. But the usual logs don't reveal anything
extra-ordinary. The cluster ist healthy again for 5 days now.
Then I found some clients (CephFS mounted for home directories and
shared storage for compute nodes) reporting this multiple times:
---cut here---
[Mi Aug 22 10:31:33 2018] libceph: osd21 down
[Mi Aug 22 10:31:33 2018] libceph: osd22 down
[Mi Aug 22 10:31:33 2018] libceph: osd23 down
[Mi Aug 22 10:31:33 2018] libceph: osd24 down
[Mi Aug 22 10:31:33 2018] libceph: osd21 weight 0x0 (out)
[Mi Aug 22 10:31:33 2018] libceph: osd22 weight 0x0 (out)
[Mi Aug 22 10:31:33 2018] libceph: osd23 weight 0x0 (out)
[Mi Aug 22 10:31:33 2018] libceph: osd24 weight 0x0 (out)
[Mi Aug 22 10:31:33 2018] libceph: osd21 weight 0x10000 (in)
[Mi Aug 22 10:31:33 2018] libceph: osd21 up
[Mi Aug 22 10:31:33 2018] libceph: osd22 weight 0x10000 (in)
[Mi Aug 22 10:31:33 2018] libceph: osd22 up
[Mi Aug 22 10:31:33 2018] libceph: osd24 weight 0x10000 (in)
[Mi Aug 22 10:31:33 2018] libceph: osd24 up
[Mi Aug 22 10:31:33 2018] libceph: osd23 weight 0x10000 (in)
[Mi Aug 22 10:31:33 2018] libceph: osd23 up
---cut here---
This output repeats about 20 times per OSD (except for osd20, only one
occurence). But there's no health warning, no trace of that in the
logs, no flapping (yet?), as if nothing has happened. Since these are
those OSDs that were affected by flapping there has to be a
connection, but I can't seem to find it.
Why isn't there anything in the logs related to these dmesg events?
Why would a client report OSDs down if they haven't been? We checked
the disks for errors, we searched for network issues, no hint for
anything going wrong.
Can anyone shed some light on this? Can these client messages somehow
affect the OSD/MON communication in such way that MON starts reporting
OSDs down, too? The OSDs then report themselves up and then the
flapping begins?
How can I find the cause for these reports?
If there's any more information I can provide, please let me know.
Any insights are highly appreciated!
Regards,
Eugen
[1] http://tracker.ceph.com/issues/23352
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