ElasticSearch replication

Question

Can somebody provide some instructions on how to configure ElasticSearch for replication. I am running ES in windows and understand that if I run the bat files multiple times on the same server, a separate instance of ES is started and they all connect to each other.

I will be moving to a production environment soon and will have a three node set up, each node being on a different server. Can someone point me at some documentation which gives me a bit more control of the replication set up.

Answer 1

Have a look at the discovery documentation . It works out-of-the-box with multicast discovery, even though you could have problems with firewalls etc., but I would recommend against it in production. I would rather use unicast and configure the host names of the nodes belonging to the cluster in the elasticsearch.yml . That way you make sure nobody is going to join the production cluster from his own machine.

One other thing I would do is configure a proper cluster name specific for every environment.

Answer 2

Replication is set to each index in Elasticsearch, not set to the server or node. That is, each index can have different number of replication setting. The number of replica setting is 1 by default.

The number of replication is not related or restricted to number of node set up. If the number of replication is greater than the number of data nodes, only the index health becomes yellow since some replications are not allocated, anything still works fine.

You can reference to the document for further information: https://www.elastic.co/guide/en/elasticsearch/reference/current/indices-update-settings.html