# What is the minimum number of servers necessary for healthy elastic search cluster?

**URL:** <https://discuss.elastic.co/t/what-is-the-minimum-number-of-servers-necessary-for-healthy-elastic-search-cluster/244977>\
**Category:** Elasticsearch\
**Created:** [August 14, 2020, 8:54am UTC](https://discuss.elastic.co/t/what-is-the-minimum-number-of-servers-necessary-for-healthy-elastic-search-cluster/244977 "2020-08-14T08:54:14Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Ankitha\_Sathya](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/ankitha_sathya/32/73871_2.png) [@Ankitha\_Sathya](https://discuss.elastic.co/u/Ankitha_Sathya)\
**Post date:** [August 14, 2020, 8:54am UTC](https://discuss.elastic.co/t/what-is-the-minimum-number-of-servers-necessary-for-healthy-elastic-search-cluster/244977/1 "2020-08-14T08:54:15Z")

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Hi all,

I am new to Elastic search and trying to understand what is the minimum requirement for a ES cluster keeping availability in mind.  
Note that I am considering all the nodes are master-eligible and data node and running Elastic-Search -7.8.

I started with minimum 2 nodes setup for this. Since we have master and data nodes here. By default all nodes are master-eligible unless otherwise specified. Say node 1 is master and node 2 is data (master-eligible). Say node-1 is down , then the only available node is 2 and it becomes master. But what if there is a network break between these nodes? Then node-1 will still be master but node-2 thinks node-1 is down and it elects itself as a master. When the connectivity is restored we have 2 masters for a cluster.

So next option was to have 3 nodes : In this case say node-1 is the master and it is down . We have node-2 and node-3 which have the right to vote for master elections and it may happen that node-2 elects itself for master and node-3 does the same. Now the cluster does not have a master.

The 4 node theory seemed slightly better than others. A master node going down would cause 3 nodes in the cluster to be up and in that use-case we will not face split brain. Having said that if 2 nodes goes down , we will still face the same , but the chances are less.

The question is regarding the statement with 3 node setup where there is no majority on voting. Is this really possible or ES is intelligent enough to come to a conclusion and have a master node?

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**Author:** ![Christian\_Dahlqvist](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/christian_dahlqvist/32/4617_2.png) [@Christian\_Dahlqvist](https://discuss.elastic.co/u/Christian_Dahlqvist)\
**Post date:** [August 14, 2020, 9:22am UTC](https://discuss.elastic.co/t/what-is-the-minimum-number-of-servers-necessary-for-healthy-elastic-search-cluster/244977/2 "2020-08-14T09:22:30Z")

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You need a minimum of 3 hosts/nodes. Read [this part of the docs](https://www.elastic.co/guide/en/elasticsearch/reference/7.8/high-availability-cluster-small-clusters.html) for more information.

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**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [September 11, 2020, 9:22am UTC](https://discuss.elastic.co/t/what-is-the-minimum-number-of-servers-necessary-for-healthy-elastic-search-cluster/244977/3 "2020-09-11T09:22:37Z")

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