how many shards and replicas should be set for Elastic Search

https://cpratt.co/how-many-shards-should-elasticsearch-indexes-have/

https://blog.trifork.com/2014/01/07/elasticsearch-how-many-shards/

https://www.elastic.co/guide/en/elasticsearch/guide/current/replica-shards.html

https://cpratt.co/how-many-nodes-should-an-elasticsearch-cluster-have/

https://stackoverflow.com/questions/22544461/elasticsearch-optimal-number-of-shards-per-node

https://www.elastic.co/guide/en/elasticsearch/guide/current/replica-shards.html