Elasticsearch shard allocation algorithm

Demystifying shard allocation internals in Elasticsearch Note: This intended for people who want to understand internal workings of Elasticsearch shard allocation Shard Allocation in ES is provided as service component named AllocationService. AllocationService is initiated and started by ClusterModule which is run in Master node and manages entire cluster level actions. AllocationService is initiated here: AllocationService Github link What AllocationService does ? This service manages the node allocation of a cluster.
Read more...