Cluster not responding to status requests

Elastic Stack Elasticsearch
1

Hi,

I am experiencing a very strange behavoir at the moment. I have an
eight-node cluster, cluster is up and running (status green), I can send
search request and get responses, I can ask for cluster health and cluster
state, and thats it. I dont get any answer on cluster nodes, stats,
segments, nothing, no response.
Last thing I did was writing 5m docs in two indices, that worked fine.
Does anyone ever experienced something similar? Any hints what to do to get
the cluster back responding (apart from restart)? Any idea what could be
the reason for this?

Thanks in advance!
Andrej

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2

Ok, after this seemed to be reproducable I looked around a bit more in
several log files, it seems that something brought an optimization process
to halt (on one node), blocking further optimizations. So whenever I try to
optimize an index I will get the following exception and can not retrieve
stats anymore:

[2012-08-27 17:45:21,680][DEBUG][action.admin.indices.optimize] [Pulse]
[xxxxxx][14], node[xxxxx], [R], s[STARTED]: Failed to execute
[org.elasticsearch.action.admin.indices.optimize.OptimizeRequest@1d40c0cf]
org.elasticsearch.transport.RemoteTransportException:
[Butterball][inet[/x.x.x.x:xxxx]][indices/optimize/s]
Caused by: org.elasticsearch.index.engine.FlushNotAllowedEngineException:
[xxxxx][14] Already flushing...

Maybe someone can tell me if there is a connection between the optimize
problem and the "no stats" problem?

Thanks!
Andrej

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