Index, Shard and Raplica mapping

Elastic Stack Elasticsearch
1

https://www.elastic.co/guide/en/elasticsearch/reference/current/_basic_concepts.html

In the basic concepts, it is mentioned about the number of default 5 shared and 1 replica get created for an index, and if their are 2 nodes in an index, it creates 5 shared and 5 replica. What combination does all 5 replica have?

Shard and Replica mapping.jpg683×501 29.9 KB

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And also how the replica will increase if I have 3 nodes

3

You set the number of shards and replicas per index. If you set an index to have 5 shards and 1 recplica, meaning that for every primary shard there is 1 replica shard so in total you will have 5 replicas. Now if you have 2 nodes, the 5 primary and 5 replicas will be distributed around the 2 nodes. If you have 3 nodes, the same 5 primary and 5 replicas shards will be distributed evenly around the 3 nodes.