Hi,
The problem with this shard is likely due to this event in your logs: [2016-02-21 18:08:29,172][WARN ][index.engine ] [instance-0000000009] [location-541275-1602][0] failed engine [merge failed] org.apache.lucene.index.MergePolicy$MergeException: java.lang.OutOfMemoryError: Direct buffer memory at org.e …
The OutOfMemory-event should normally trigger a node-restart, and we're looking into why that does not happen. I've restarted your node.
To avoid this OOM-events at all, which any production cluster must, you'll need to reduce your memory requirements and/or upgrade the cluster. Production clusters should also use the high availability offerings, so there's replicas in multiple availability zones. The memory pressure indicator shows the current memory pressure. Your OOM seems to be caused by a sudden increase, e.g. due to overwhelming the cluster with concurrent index requests that queue up.