# Merging ES Clusters **URL:** \ **Category:** Elasticsearch\ **Created:** [June 6, 2022, 4:56am UTC](https://discuss.elastic.co/t/merging-es-clusters/306419 "2022-06-06T04:56:24Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![Moe\_Hmaidan](https://avatars.discourse-cdn.com/v4/letter/m/8e8cbc/32.png) [@Moe\_Hmaidan](https://discuss.elastic.co/u/Moe_Hmaidan)\ **Post date:** [June 6, 2022, 4:56am UTC](https://discuss.elastic.co/t/merging-es-clusters/306419/1 "2022-06-06T04:56:24Z")
Hi All, **We have two clusters:-** - Cluster A we have 5 new nodes running ES v7.17 (All data nodes out of which two are master) - Cluster A Contains no data what so ever it was meant to be a backup cluster but now they want it to be active - Cluster B 10 active nodes Running ES v7.9.3(All data nodes, 2 master). - Cluster B Contains data that can be backed up using snapshot repository. Can someone suggest how to merge these two cluster because we were asked to. **Need to meet below two conditions:** - No data loss. - Minimal downtime. **My idea was to go about it by doing the following** 1. backup cluster B using snapshot 2. redirect all data sources to cluster A 3. update all cluster B ES to 7.17 4. Vote out nodes one by one from Cluster B 5. Generate a new UUID on said node or delete the /data directory which contains the current UUID 6. setup ES conf on node to join cluster A 7. After all nodes are moved backup the snapshot to the new cluster **I did not proceed with my takeaway because of l:** 1. I just don't know if this will work and how to proceed with step number 5 to get rid of the old UUID 2. can i backup the snapshot to the new cluster to retrieve old data _Thanks in advance_ ---
**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:** [June 6, 2022, 5:17am UTC](https://discuss.elastic.co/t/merging-es-clusters/306419/2 "2022-06-06T05:17:42Z")
I would recommend instead doing the following: 1. Make another node in cluster A a master node. [You should always have at least 3 master eligible nodes in any cluster](https://www.elastic.co/guide/en/elasticsearch/reference/7.17/high-availability-cluster-design.html). Having just 2 nodes does not allow one of the master eligible noides to go down without making the cluster unavailable. 2. Perform a [rolling upgrade](https://www.elastic.co/guide/en/elasticsearch/reference/7.17/rolling-upgrades.html) of cluster A to Elasticsearch 7.17. Take a snapshot prior to the upgrade. 3. Shut down all nodes in cluster B, clear the data path, change the config and restart them so they can join cluster A as data nodes. ---
**Author:** ![Moe\_Hmaidan](https://avatars.discourse-cdn.com/v4/letter/m/8e8cbc/32.png) [@Moe\_Hmaidan](https://discuss.elastic.co/u/Moe_Hmaidan)\ **Post date:** [June 6, 2022, 5:25am UTC](https://discuss.elastic.co/t/merging-es-clusters/306419/3 "2022-06-06T05:25:08Z")
I apologize cluster A is actually configured to have 3 master-eligible nodes I learned from my mistakes. I'll try to do as you said but just to be make it clear by clearing the data you mean all of the Elasticsearch.conf directive " **path.data**" content and folder am i right? ---
**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:** [June 6, 2022, 5:27am UTC](https://discuss.elastic.co/t/merging-es-clusters/306419/4 "2022-06-06T05:27:09Z")
> [@Moe\_Hmaidan](#): > > I'll try to do as you said but just to be make it clear by clearing the data you mean all of the Elasticsearch.conf directive " **path.data**" content and folder am i right? Yes, the nodes in cluster B need to join as completely new data nodes that have no knowledge of being part of any prior cluster. ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [July 4, 2022, 5:27am UTC](https://discuss.elastic.co/t/merging-es-clusters/306419/5 "2022-07-04T05:27:21Z")
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