How to check if a master node auto-election is enabled?

Elastic Stack Elasticsearch
1

We have installed ES 6.2.4 and have 3 master node setup.

  1. Is there a way to check if auto-election of master node is enabled in case active master goes down?
  2. do elastic search always do auto-election (or) disabling auto-election is also allowed in some es versions?

Note: we have set "discovery.zen.minimum_master_nodes: 2" such that split brain won't occur.

2

Yes, elections are automatic and no, that cannot be disabled. I can't imagine why you might want to prevent the election of a new master when the old one fails.

You are using a very old version, long past EOL, and should upgrade as a matter of urgency.

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3

@DavidTurner, Thanks for the quick response. I'm actually going through ES documentation and comparing the same with the readymade prod cluster we have. Nowhere I was able to find out if auto election is strictly automatic in the docs (May be I didn't read it properly). So, I was looking for a config that enables/disables auto-master election in the nodes elasticsearch.toml files to see if it's set to true.

Thanks again!. We will soon migrate to newer version.

As a follow up question, if the active Master goes down, from the remaining 2 master-eligible nodes, either of them can become active master. But which nodes are involved in the selection process? Only datanodes?

4

Maybe see these docs?

Discovery is the process by which the cluster formation module finds other nodes with which to form a cluster. This process runs when you start an Elasticsearch node or when a node believes the master node failed and continues until the master node is found or a new master node is elected.

Disabling this makes no sense.

Only the master-eligible nodes.

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5

@DavidTurner Yes, only the master-eligible nodes can become next Master.
I'll rephrase,
Which nodes elect/vote the master-eligible nodes?

In this doc: Zen Discovery | Elasticsearch Reference [6.2] | Elastic

Under "Master Election" section, it says, "When the master node stops or has encountered a problem, the cluster nodes start pinging again and will elect a new master."

Do "cluster nodes" here mean only "datanodes" or "masternodes" or both.

6

As I said, only the master-eligible nodes are involved in the selection process, although all the nodes perform pinging.

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