Hi, I have a cluster with 29 physical servers running ElasticSearch 2.2.1. Three of the servers are dedicated master nodes and I am running 2 datanodes in each of the other servers (this is 52 datanodes in total). I am creating one index per day with 7 shards and 1 replica.
All the datanodes have the cluster.routing.allocation.same_shard.host: true parameter in the elasticsearch.yml and the network.host parameter is the same for each datanodes pair sharing the same physical host, but for some reason I see some shards with its primary and replica allocated on the same physical server.
Am i missing something here?
Of course I can fix this rerouting the shard to another server or using the shard allocation awareness, but I'd like to understand why is this happening.