Replica Shards | Elasticsearch: The Definitive Guide [2.x] | ElasticIMPORTANT: This documentation is no longer updated. Refer to Elastic's version policy and the latest documentation. Up until now we have spoken only about primary shards, but we have another tool in our belt: replica shards. The main purpose of replicas is for failover, as discussed in Life Inside a Cluster: if the node holding a primary shard dies, a replica is promoted to the role of primary. At
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