More master node?

Elastic Stack Elasticsearch
1

Hello everyone, I explain my context.
I am designing an architecture with 18 nodes where everyone can be master (of the 18 nodes, only 1 master remains) if necessary, but I feel that 1 for 17 is too little and I want to put 3 masters.
Is there the possibility of adding N amount of master without having dedicated ones?
I am using version 8.6


cluster.name: MYCLUSTER
discovery.seed_hosts: ["123.188.49.31", "123.188.49.33", "123.188.49.34", "123.188.49.76", "123.188.49.79", "123.188.49.80", "123.188.49.87", "123.188.49.144", "123.188.49.147", "123.176.49.21", "123.176.49.23", "123.176.49.24", "123.176.49.31", "123.176.49.77", "123.176.49.78", "123.176.49.80", "123.176.49.81", "123.176.49.82"]
cluster.initial_master_nodes: ["Node01", "Node02", "Node03", "Node04", "Node05", "Node06", "Node07", "Node08", "Node09", "Node10", "Node11", "Node12", "Node13", "Node14", "Node15", "Node16", "Node17", "Node18"]
2

I don't see a reason to have these many master.
moret master you have more syncing will happen between them as they have to keep each other up-to-date about all information.

I would keep 3 or max 5 master as cluster will still survive if two of them goes down togather.

also cluster.initial.master_nodes have to be used only one time when you create a cluster. once cluster is created you don't need that. you have all the node listed there.

3

Can you give more context of what you want to achieve with this architecture?

Why you feel that? On a elasticsearch cluster only one node will be the master, you can have N master-eligible nodes, but only one will be the master, if the master node goes down for any reason, another master-eligible node will assume the role.

The best approach, and the recommendation, is to have dedicated master, at least 3 dedicated master nodes.

4

Specifically, the official docs say so here:

Clusters with more than three nodes

...
However, it is good practice to limit the number of master-eligible nodes in the cluster to three.

1 Like
5

Thank you very much for your answer.
Well, I have a customer who has 18 nodes ready to create a licensed elasticsearch cluster. I had thought of a design where any of the 18 nodes could be master but consulting the elastic documentation and reviewing the forum I found that the vast majority used more than 1 master node.
I raised the cluster and put the configuration in checkups.opster.com where it also recommended having at least 3 master nodes

So the only way to have more than 1 master node is to make it dedicated, right?
I wanted to find a way to automatically choose 2 or 3 master nodes instead of just 1.

6

Thank you very much @DavidTurner @elasticforme , I will continue reading the documentation to find a good solution.

7

Your cluster will only have one node acting as the master node, this is how elasticsearch works, you will have other master eligible nodes that can assume the role of the master node if the current master fails.

For example, if you have 3 dedicated master nodes, only one will be the elected master, the other two will be in stand-by to assume the role in case of a failure, the same applies to N number of master eligible nodes.

8

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