CODEWITHSUNDEEP
elasticsearchreplicationhigh-availability
Vovan Kuznetsov
Vovan Kuznetsov

Reputation: 491

High availability in two node Elasticsearch cluster

We have a requirement to run highly available Elasticsearch cluster with only two nodes. I understand for reliable HA it is recommended to have odd number of nodes (3+) but cannot do that because of some particular environment restrictions.

In ES 6.x we could achieve that by setting discovery.zen.minimum_master_nodes config option to 1, this allows to keep remaining node UP in case of single node failure ( https://blog.trifork.com/2013/10/24/how-to-avoid-the-split-brain-problem-in-elasticsearch/ ). This comes at cost of potential data inconsistency but that's something we know how to deal with.

Now, in ES 7.x. discovery.zen.minimum_master_nodes option has no effect anymore. Is there any way to achieve similar behavior with ES 7.x on two node cluster, i.e. keep high availability at cost of losing some data integrity when split-brain occurs?

Upvotes: 1

Views: 1040

Answers (1)

Sandeep Kanabar
Sandeep Kanabar

Reputation: 1302

Please have a look at this excellent blog post that explains in detail about the changes in cluster co-ordination in ES 7.x

Per the breaking changes, The discovery.zen.minimum_master_nodes setting is permitted, but ignored, on 7.x nodes. Instead you configure discovery.seed_hosts and cluster.initial_master_nodes as mentioned here.

Upvotes: 1

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