Out of interest what do you find hard about running ElasticSearch clusters? In my experience ES has been one of the easiest clustered / highly available and sh

Out of interest what do you find hard about running ElasticSearch clusters? In my experience ES has been one of the easiest clustered / highly available and sharded systems I've ever run - especially for how incredibly performant and reliable it is. I've generally found that beyond right sizing your nodes, indexes and shard configuration - it pretty much just works without ever really having issues.