We use ElasticSearch more and more here at Sematext (we have a number of ElasticSearch projects right at this moment, some of them quite massive in terms of data and/or query volume). In our work we typically have only 1 ElasticSearch instance/only 1 JVM running ElasticSearch on each server in the cluster.
How about you? Do you run multiple ElasticSearch instances/JVMs per box in production?
Thank you for your feedback!