I'm embarrassed to say that at the present moment we currently don't use ES clustering but rather a monstrous powerful bare metal machine as we had issues with the cluster failing with some network issues we had with Rackspace.

BTW I didn't mean to denigrate Elastic Search (I assume that is why I'm getting downvoted.... a comment would help). We just haven't had the chance to upgrade it and properly configure it.

In fact Elastic has been pretty darn speedy as of lately particularly since we purge some of the data after 6 months (we still have permanent filesystem storage of logs of course).