When starting your Elasticsearch node, one of the first things that happens is looking for a master node that has the same cluster name and is visible. If a master is found, the node gets joined into an already formed cluster. If no master is found, then the node itself is selected as a master (of course if the configuration allows such behavior). The process of forming a cluster and finding nodes is called discovery. The module responsible for discovery has two main purposes: electing a master and discovering new nodes within a cluster. In this section, we will discuss how we can configure and tune the discovery module.
By default, without installing additional plugins, Elasticsearch allows us to use Zen discovery, which provides us with unicast discovery. Unicast (http://en.wikipedia.org/wiki/Unicast) allows transmission of a single message over the network to a single host at once. Elasticsearch node sends the message to the nodes defined in...