# Setting up a basic high availability cluster **URL:** \ **Category:** Elasticsearch\ **Created:** [August 20, 2018, 4:19pm UTC](https://discuss.elastic.co/t/setting-up-a-basic-high-availability-cluster/145206 "2018-08-20T16:19:03Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![tim2](https://avatars.discourse-cdn.com/v4/letter/t/b782af/32.png) [@tim2](https://discuss.elastic.co/u/tim2)\ **Post date:** [August 20, 2018, 4:19pm UTC](https://discuss.elastic.co/t/setting-up-a-basic-high-availability-cluster/145206/1 "2018-08-20T16:19:03Z")
Im planning to set up a high availability cluster with 2 physical host machines hosting a number of VMs / elasticsearch nodes How many nodes do I need on each host machine so that I can safely restart a host machine and keep everything operational? data integrity is crucial, can't lose any data Would this work? 2 nodes on each host machine Host A: node 1, node 2 Host B: node 3, node 4 or is this no different than having 1 node per host? or is there a better config for the cluster? Thanks ---
**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 20, 2018, 5:18pm UTC](https://discuss.elastic.co/t/setting-up-a-basic-high-availability-cluster/145206/2 "2018-08-20T17:18:17Z")
To set up a highly available cluster you need a minimum of 3 hosts so that you can reach a majority even with 1 host unavailable. ---
**Author:** ![tim2](https://avatars.discourse-cdn.com/v4/letter/t/b782af/32.png) [@tim2](https://discuss.elastic.co/u/tim2)\ **Post date:** [August 20, 2018, 5:29pm UTC](https://discuss.elastic.co/t/setting-up-a-basic-high-availability-cluster/145206/3 "2018-08-20T17:29:34Z")
would having 3 hosts guarantee no data loss when restarting 1 host machine at a time? (eg: OS updates) should the number of hosts always be an odd number? eg: 3,5,7? does elasticsearch distribute the workload based on available host resources (eg: cpu usage, disk performance)? or is it random? ---
**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 20, 2018, 5:54pm UTC](https://discuss.elastic.co/t/setting-up-a-basic-high-availability-cluster/145206/4 "2018-08-20T17:54:42Z")
> [@tim2](#): > > would having 3 hosts guarantee no data loss when restarting 1 host machine at a time? (eg: OS updates) Yes, assuming that you have at least one replica configured for all indices. > [@tim2](#): > > should the number of hosts always be an odd number? eg: 3,5,7? No, but you need a minimum of 3 master-eligible nodes on separate hosts. > [@tim2](#): > > does elasticsearch distribute the workload based on available host resources (eg: cpu usage, disk performance)? or is it random? The cluster handles the load and any request can be sent to any node. Exactly how load is distributed is however a large topic. ---
**Author:** ![tim2](https://avatars.discourse-cdn.com/v4/letter/t/b782af/32.png) [@tim2](https://discuss.elastic.co/u/tim2)\ **Post date:** [August 20, 2018, 6:20pm UTC](https://discuss.elastic.co/t/setting-up-a-basic-high-availability-cluster/145206/5 "2018-08-20T18:20:58Z")
> Yes, assuming that you have at least one replica configured for all indices. so basically I just need to set up a cluster with 3 nodes on 3 separate hosts with the default settings for primary and replica shards? and elasticsearch will automatically manage the shards, etc.? > The cluster handles the load and any request can be sent to any node. Exactly how load is distributed is however a large topic. when running a request (index or search), does it have to be sent to the current master node or any node in the cluster is fine? does the client need to know the IPs of all the nodes? or any node IP will work, but it's good to know all in case of connection failure? thanks ---
**Author:** ![chandra0651](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/chandra0651/32/30484_2.png) [@chandra0651](https://discuss.elastic.co/u/chandra0651)\ **Post date:** [August 20, 2018, 7:07pm UTC](https://discuss.elastic.co/t/setting-up-a-basic-high-availability-cluster/145206/6 "2018-08-20T19:07:36Z")
so basically I just need to set up a cluster with 3 nodes on 3 separate hosts with the default settings for primary and replica shards? and elasticsearch will automatically manage the shards, etc.? ` > For 3 node cluster the best suggested settings for index should some thing be like 3 primary and one replica which can handle the failure of one host. ` ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [September 17, 2018, 7:07pm UTC](https://discuss.elastic.co/t/setting-up-a-basic-high-availability-cluster/145206/7 "2018-09-17T19:07:39Z")
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