# How to change single-node-cluster to 3 node cluster?

**URL:** <https://discuss.elastic.co/t/how-to-change-single-node-cluster-to-3-node-cluster/186633>\
**Category:** Elasticsearch\
**Created:** [June 20, 2019, 9:24am UTC](https://discuss.elastic.co/t/how-to-change-single-node-cluster-to-3-node-cluster/186633 "2019-06-20T09:24:07Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![asp](https://avatars.discourse-cdn.com/v4/letter/a/9fc348/32.png) [@asp](https://discuss.elastic.co/u/asp)\
**Post date:** [June 20, 2019, 9:24am UTC](https://discuss.elastic.co/t/how-to-change-single-node-cluster-to-3-node-cluster/186633/1 "2019-06-20T09:24:07Z")

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Hi,

If I decide to start with a single node ES cluster (version 7.1.1) where I set `discovery.type` to `single-node`.  
What is the path to go for migrate this cluster to a 3 node cluster? All data of the cluster needs to be kept.

Just change discovery.type, add `discovery.seed_hosts` which contains all 3 hosts and add `cluster.initial_master_nodes` which contains the nodes names?  
Then (re-)starting all nodes and I am done?

Or is there more to do?

And how to change the number of replicas for existing indices?

Thanks,  
Andreas

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**Author:** ![MKU](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/mku/32/48327_2.png) [@MKU](https://discuss.elastic.co/u/MKU)\
**Post date:** [June 20, 2019, 9:44am UTC](https://discuss.elastic.co/t/how-to-change-single-node-cluster-to-3-node-cluster/186633/2 "2019-06-20T09:44:19Z")

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yes, do that in all nodes

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**Author:** ![DavidTurner](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/davidturner/32/22453_2.png) [@DavidTurner](https://discuss.elastic.co/u/DavidTurner)\
**Post date:** [June 20, 2019, 1:32pm UTC](https://discuss.elastic.co/t/how-to-change-single-node-cluster-to-3-node-cluster/186633/3 "2019-06-20T13:32:58Z")

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This is not quite true. You should set `discovery.seed_hosts` on every node, but you should not set `cluster.initial_master_nodes` on any of them. This is only used the first time the cluster starts, but that's already happened, so you shouldn't set it when growing a cluster.

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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:** [July 18, 2019, 1:33pm UTC](https://discuss.elastic.co/t/how-to-change-single-node-cluster-to-3-node-cluster/186633/4 "2019-07-18T13:33:04Z")

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