# Elastic 2 Cluster Setup upgrade

**URL:** <https://discuss.elastic.co/t/elastic-2-cluster-setup-upgrade/244737>\
**Category:** Elasticsearch\
**Created:** [August 12, 2020, 2:24pm UTC](https://discuss.elastic.co/t/elastic-2-cluster-setup-upgrade/244737 "2020-08-12T14:24:10Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![adwaitjoshi](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/adwaitjoshi/32/35098_2.png) [@adwaitjoshi](https://discuss.elastic.co/u/adwaitjoshi)\
**Post date:** [August 12, 2020, 2:24pm UTC](https://discuss.elastic.co/t/elastic-2-cluster-setup-upgrade/244737/1 "2020-08-12T14:24:10Z")

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I have 2 elastic machines

M1 and M2

They both are master eligible and replicas of each other. I need to rebuild M1. But when I do that and reinstall everything on this box. M1 doesn't join back M2. I am assuming that M2 is eligible but not becoming master and may have to do with "voting rights".

How do I make it work so after a hardware and OS upgrade M1 will join M2 back and become the master and copy the data

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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 12, 2020, 3:03pm UTC](https://discuss.elastic.co/t/elastic-2-cluster-setup-upgrade/244737/2 "2020-08-12T15:03:05Z")

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Which version are you using?

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**Author:** ![adwaitjoshi](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/adwaitjoshi/32/35098_2.png) [@adwaitjoshi](https://discuss.elastic.co/u/adwaitjoshi)\
**Post date:** [August 12, 2020, 3:35pm UTC](https://discuss.elastic.co/t/elastic-2-cluster-setup-upgrade/244737/3 "2020-08-12T15:35:48Z")

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Version 7.8

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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 12, 2020, 3:52pm UTC](https://discuss.elastic.co/t/elastic-2-cluster-setup-upgrade/244737/4 "2020-08-12T15:52:02Z")

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If you only have 2 master eligible nodes I believe you can not just rebuild one server as you then lose half the master eligible nodes which means a master can no longer be elected. Before you rebuild, make sure you take a snapshot and then [remove the master node to be rebuilt](https://www.elastic.co/guide/en/elasticsearch/reference/7.8/add-elasticsearch-nodes.html).

I would also recommend you read [this](https://www.elastic.co/guide/en/elasticsearch/reference/current/high-availability-cluster-small-clusters.html).

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**Author:** ![Steve\_Mushero](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/steve_mushero/32/22441_2.png) [@Steve\_Mushero](https://discuss.elastic.co/u/Steve_Mushero)\
**Post date:** [August 13, 2020, 2:44am UTC](https://discuss.elastic.co/t/elastic-2-cluster-setup-upgrade/244737/5 "2020-08-13T02:44:19Z")

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@Christian_Dahlqvist, from those docs, wouldn't easiest path be EITHER of:

1. Set master-eligible false on M1 node and restart it so it's data node only, then after cluster is stable, stop & rebuild M1. If need to rebuild later, swap master roles (M1.true, rejoin, M2.false, rejoin, stop & rebuild).

2. Add small voting-only node somewhere, then rebuild M1 any time.

I'd think #1 easiest.

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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 10, 2020, 2:44am UTC](https://discuss.elastic.co/t/elastic-2-cluster-setup-upgrade/244737/6 "2020-09-10T02:44:52Z")

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Closed on September 10, 2020, 2:44am UTC

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