Hi,
I have a cluster of 5 hosts running Ceph 0.94.6 on CentOS 6.5. On each host, there is 1 monitor and 13 OSDs. We had an issue with the network and for some reason (which I still don't know why), the servers were restarted. One host is still down, but the monitors on the 4 remaining servers are failing to enter a quorum.
I managed to get a quorum of 3 monitors by stopping all Ceph monitors and OSDs across all machines, and bringing up the top 3 ranked monitors in order of rank. After a few minutes, the 60z0m02 monitor (the top ranked one) became the leader:
{
"name": "60z0m02",
"rank": 0,
"state": "leader",
"election_epoch": 11328,
"quorum": [
0,
1,
2
],
"outside_quorum": [],
"extra_probe_peers": [],
"sync_provider": [],
"monmap": {
"epoch": 5,
"fsid": "2f51a247-3155-4bcf-9aee-c6f6b2c5e2af",
"modified": "2016-04-28 22:26:48.604393",
"created": "0.000000",
"mons": [
{
"rank": 0,
"name": "60z0m02",
"addr": "10.98.2.166:6789\/0"
},
{
"rank": 1,
"name": "60zxl02",
"addr": "10.98.2.167:6789\/0"
},
{
"rank": 2,
"name": "610wl02",
"addr": "10.98.2.173:6789\/0"
},
{
"rank": 3,
"name": "618yl02",
"addr": "10.98.2.214:6789\/0"
},
{
"rank": 4,
"name": "615yl02",
"addr": "10.98.2.216:6789\/0"
}
]
}
}
The other 2 monitors became peons:
"name": "60zxl02",
"rank": 1,
"state": "peon",
"election_epoch": 11328,
"quorum": [
0,
1,
2
],
"name": "610wl02",
"rank": 2,
"state": "peon",
"election_epoch": 11328,
"quorum": [
0,
1,
2
],
I then proceeded to start the fourth monitor, 615yl02 (618yl02 is powered off), but after more than 2 hours and several election rounds, the monitors still haven't reached a quorum. The monitors alternate mostly between "election", "probing" states but they often seem to be in different election epochs.
Is this normal?
Is there anything I can do to help the monitors elect a leader? Should I manually remove the dead host's monitor from the monitor map?
I left all OSD daemons stopped while the election is going on purpose. Is this the best thing to do? Would bringing the OSDs up help or complicate matters even more? Or doesn't it make any difference?
I don't see anything obviously wrong in the monitor logs. They're mostly filled with messages like the following:
2016-07-25 14:17:57.806148 7fc1b3f7e700 1 mon.610wl02@2(electing).elector(11411) init, last seen epoch 11411
2016-07-25 14:17:57.829198 7fc1b7caf700 0 log_channel(audit) log [DBG] : from='admin socket' entity='admin socket' cmd='mon_status' args=[]: dispatch
2016-07-25 14:17:57.829200 7fc1b7caf700 0 log_channel(audit) do_log log to syslog
2016-07-25 14:17:57.829254 7fc1b7caf700 0 log_channel(audit) log [DBG] : from='admin socket' entity='admin socket' cmd=mon_status args=[]: finished
Any help would be hugely appreciated.
Thanks,
Sergio
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