Node configuration of elasticsesarch cluster

Elastic Stack Elasticsearch
1

Hi,

i'm starting getting into elasticsearch cluster, and i have read many time the recomendation to have 3 master eligible nodes to have high availability.

I've also read that if you have dedicated master nodes should not be used for indexing or requests. However if a node if data and master it can, for instance in a 3 node configuration where each node is master/data node you could send requests to any of them.

So first question: whats the difference on being master only node and master/data node? if i should not send requests to a master only node, i thing a master/data node has more work to do than a master only node, so why should i send request to the first and not the later?

My other question is if the following configuration is a valid variation from the 3 node configuration:
node1 Master/data node
node2 Master/data node
node3 Master/data node (voting only)

in this configuration node3 will never act as master, will only participate in voting, i still can loose any of the 3 nodes as soon as there are 2 running, and i could direct requests to node3 as it will never be a master. Is that OK?

thanks

2

Typically you don't have both master-only and mixed master/data nodes in a cluster. Mixed nodes are used in smaller, lightly-loaded clusters where there's no risk of overloading anything so it doesn't really matter where you send your requests. Dedicated masters are appropriate where the cluster is more heavily loaded and there it is important to keep as much load as possible off the masters.

Yes it is.

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3

Thanks David for the answer!
regards

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