The cluster coordinator provides a mechanism for the nodes (represented by the Dgraph processes running on each of the servers) to communicate with each other while ensuring increased availability of the Oracle Endeca Server.
It ensures that all systems in the cluster coordinate their actions relative to all other systems running in your environment. If one of the nodes communicates any cluster information, all other nodes recognize it and react to it in a manner that ensures synchronization, event notification, and coordination between the nodes.
The communication and coordination mechanisms continue to work in the case when connections or cluster nodes fail.
On Linux, when you run the clusterCoordinator script, all output is by default sent to the zookeeper.out file stored in the current directory. You can override the destination of the log file by setting the environment variable ZOO_LOG_DIR before running the script. On Windows, when you run the clusterCoordinator script, all output is logged in a separate command window.
The Cluster Coordinator service must be running on at least one node before starting the Dgraph process and its data store on any of the physical servers.
It is recommended that you start a single Cluster Coordinator service on the node that will be designated as the leader node, and then start the Dgraph processes on all servers by referencing the host and port of the Cluster Coordinator.