What is cluster in ElasticSearch?

1.	What is cluster in ElasticSearch?
Answer» A cluster is a COLLECTION of connected nodes. If you run only one instance or node of Elasticsearch, then you have a single-node cluster or a cluster of one node. CLUSTERS automatically REORGANIZE themselves when nodes join or leave so the data is DISTRIBUTED evenly among all the nodes. Despite being fully functional, the cluster is at risk of data LOSS if it fails.

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