On 07/25/2016 03:41 PM, Sergio A. de Carvalho Jr. wrote:
In the logs, there 2 monitors are constantly reporting that they won the
leader election:
60z0m02 (monitor 0):
2016-07-25 14:31:11.644335 7f8760af7700 0 log_channel(cluster) log
[INF] : mon.60z0m02@0 won leader election with quorum 0,2,4
2016-07-25 14:31:44.521552 7f8760af7700 1
mon.60z0m02@0(leader).paxos(paxos recovering c 1318755..1319320) collect
timeout, calling fresh election
60zxl02 (monitor 1):
2016-07-25 14:31:59.542346 7fefdeaed700 1
mon.60zxl02@1(electing).elector(11441) init, last seen epoch 11441
2016-07-25 14:32:04.583929 7fefdf4ee700 0 log_channel(cluster) log
[INF] : mon.60zxl02@1 won leader election with quorum 1,2,4
2016-07-25 14:32:33.440103 7fefdf4ee700 1
mon.60zxl02@1(leader).paxos(paxos recovering c 1318755..1319319) collect
timeout, calling fresh election
There are two likely scenarios to explain this:
1. The monitors have different monitors in their monmaps - this could
happen if you didn't add the new monitor via 'ceph mon add'. You can
check this by running 'ceph daemon mon.<ID> mon_status' for each of the
monitors in the cluster.
2. some of the monitors are unable to communicate with each other, thus
will never acknowledge the same leader. This does not mean you have two
leaders for the same cluster, but it does mean that you will end up
having two monitors declaring victory and become the self-proclaimed
leader in the cluster. The peons should still only belong to one quorum.
If this does not help you, try setting 'debug mon = 10' and 'debug ms =
1' on the monitors and check the logs, making sure the monitors get the
probes and follow the election process. If you need further assistance,
put those logs online somewhere we can access them and we'll try to help
you out.
-Joao
On Mon, Jul 25, 2016 at 3:27 PM, Sergio A. de Carvalho Jr.
<scarvalhojr@xxxxxxxxx <mailto:scarvalhojr@xxxxxxxxx>> wrote:
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 <http://10.98.2.166:6789>\/0"
},
{
"rank": 1,
"name": "60zxl02",
"addr": "10.98.2.167:6789 <http://10.98.2.167:6789>\/0"
},
{
"rank": 2,
"name": "610wl02",
"addr": "10.98.2.173:6789 <http://10.98.2.173:6789>\/0"
},
{
"rank": 3,
"name": "618yl02",
"addr": "10.98.2.214:6789 <http://10.98.2.214:6789>\/0"
},
{
"rank": 4,
"name": "615yl02",
"addr": "10.98.2.216:6789 <http://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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