How to find quorum of the cluster in elasticsearch 7.x

Elastic Stack Elasticsearch
1

I am using Elasticsearch 7.9 version. I want to find the quorum value of my cluster.

Before 7.x version, discovery.zen.minimum_master_nodes controlled the minimum number of eligible master nodes that a node should “see” in order to operate within the cluster.

Quorum was calculated as : N/2 + 1 where N is number of master nodes. This setting was set to a quorum of master eligible nodes.

But in 7.x, the discovery.zen.minimum_master_nodes setting is permitted, but ignored, on 7.x nodes as mentioned in Breaking changes in 7.x

As per official Elasticsearch documentation on Voting configuration, I tried this below curl command:

curl -X GET "localhost:9200/_cluster/state?filter_path=metadata.cluster_coordination.last_committed_config&pretty"

And got the following output :

    {
  "metadata" : {
    "cluster_coordination" : {
      "last_committed_config" : [
        "VxTTvFWRRY6TF2Bi2vPiPw"
      ]
    }
  }
}

Can anyone please tell me how can I find the quorum value of my cluster in Elasticsearch 7.x OR how can I view the voting configuration through which I can know which master eligible nodes are participating in voting and from there I will calculate the quorum value.

2

The command you quoted is the right one, and the output is the voting configuration. This means you only have one node in the configuration, so the quorum is that single node.

3

Generally it's a mistake to look at this, however, since the cluster manages the voting configuration and may change it at any time. It's much more reliable to think of a quorum as any majority subset of the master-eligible nodes in the cluster, just as it was in 6.x.

4

Thanks @DavidTurner for your reply.

Can you please explain in detail how it's a mistake to look at this and can you also tell the difference between master election process in 6.x vs 7.x

5

As I said, it's managed by the cluster and may change at any time.

The election process is fundamentally the same in 7.x as in 6.x: a majority of the master-eligible nodes must be available at all times. The biggest difference is that the cluster manages the quorums rather than relying on users setting discovery.zen.minimum_master_nodes correctly.