We have a 21 node ES 6.3 cluster with a Hot-Warm-Cold architecture and we would like to move to have three dedicated Master nodes for this cluster and add some Coordinating nodes. As stated in the title the cluster is stable at around 80TB, because we drop older indices. We hope to mitigate some problems we've had with master election during recovery and increase search performance. Are there any recommendations of what specs these machines need?
Information about current nodes:
Hot: 4 nodes
Warm: 12 nodes
Cold: 5 nodes