We encountered a Ceph failure where the system became unresponsive with no IOPS
or throughput after encountering a failed node. Upon investigation, it appears
that the OSD process on one of the Ceph storage nodes is stuck, but ping is
still responsive. However, during the failure, Ceph was unable to recognize the
problematic node, which resulted in all other OSDs in the cluster experiencing
slow operations and no IOPS in the cluster at all.
Here's the timeline of the incident:
- At 10:40, an alert is triggered, indicating a problem with the OSD.
- After the alert, Ceph becomes unresponsive with no IOPS or throughput.
- At 11:26, an engineer discovers that there is a gradual OSD failure, with 6
out of 12 OSDs on the node being down.
- At 11:46, the Ceph engineer is unable to SSH into the faulty node and
attempts a soft restart, but the "smartmontools" process is stuck while
shutting down the server. Ping works during this time.
- After waiting for about one or two minutes, a hard restart is attempted for
the server.
- At 11:57, after the Ceph node starts normally, service resumes as usual,
indicating that the issue has been resolved.
Here is some basic information about our services:
- `Mon: 5 daemons, quorum host001, host002, host003, host004, host005 (age 4w)`
- `Mgr: host005 (active, since 4w), standbys: host001, host002, host003,
host004`
- `Osd: 218 osds: 218 up (since 22h), 218 in (since 22h)`
We have a cluster with 19 nodes, including 15 SSD nodes and 4 HDD nodes. In
total, there are 218 OSDs. The SSD nodes have 11 OSDs with Samsung EVO 870 SSD
and each drive DB/WAL by 1.6T NVME drive. We are using Ceph version 15.2.17
(8a82819d84cf884bd39c17e3236e0632ac146dc4) octopus (stable).
Here is the health check detail:
[root@node21 ~]# ceph health detail
HEALTH_WARN 1 osds down; Reduced data availability: 12 pgs inactive, 12 pgs
peering; Degraded data redundancy: 272273/43967625 objects degraded (0.619%),
88 pgs degraded, 5 pgs undersized; 18192 slow ops, oldest one blocked for 3730
sec, daemons
[osd.0,osd.1,osd.101,osd.103,osd.107,osd.108,osd.109,osd.11,osd.111,osd.112]...
have slow ops.
[WRN] OSD_DOWN: 1 osds down
osd.174 (root=default,host=hkhost031) is down
[WRN] PG_AVAILABILITY: Reduced data availability: 12 pgs inactive, 12 pgs
peering
pg 2.dc is stuck peering for 49m, current state peering, last acting
[87,95,172]
pg 2.e2 is stuck peering for 15m, current state peering, last acting
[51,177,97]
..
pg 2.f7e is active+undersized+degraded, acting [10,214]
pg 2.f84 is active+undersized+degraded, acting [91,52]
[WRN] SLOW_OPS: 18192 slow ops, oldest one blocked for 3730 sec, daemons
[osd.0,osd.1,osd.101,osd.103,osd.107,osd.108,osd.109,osd.11,osd.111,osd.112]...
have slow ops.
I have the following questions:
1. Why couldn't Ceph detect the faulty node and automatically abandon its
resources? Can anyone provide more troubleshooting guidance for this case?
2. What is Ceph's detection mechanism and where can I find related information?
All of our production cloud machines were affected and suspended. If RBD is
unstable, we cannot continue to use Ceph technology for our RBD source.
3. Did we miss any patches or bug fixes?
4. Is there anyone who can suggest improvements and how we can quickly detect
and avoid similar issues in the future?
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