ElasticSearch - Too many open files
<p>I know that this is a known and discussed problem, but I would just like to get the dimensions right here:</p>

<p>I am running <code>ElasticSearch 2.4</code> on a single <code>Ubuntu Sever 16.04 node (12 cores, 256G ram)</code>. I have increased <code>ulimit to > 130k</code> (and verified via _nodes/stats/process).</p>

<p>I have two indices with 10 shards each (since multiple nodes will join the cluster soon).</p>

<p>Now I am writing with up to 900 concurrent Java TransportClients which leads to a collapse of the ElasticSearch server within seconds, throwing a "Too many open files" Exception.</p>

<p>Am I missing something here? Are 900 concurrent writes too much for a single instance to handle? Or are 10 shards too many for one node?</p>