Where should "cluster.routing.allocation.same_shard.host" be set?

Elastic Stack Elasticsearch
6

I have the same question and it looks like I haven't found a final answer.

So if I run multiple data nodes on a single server, which elasticsearch.yml should I put cluster.routing.allocation.same_shard.host in?

  1. Only data nodes
  2. Only eligible master nodes (dedicated)?
  3. Both data nodes and eligible master nodes?

Even though I'm using Shard Allocation Awareness now, knowing the answer to this setting is helpful in the future.