I have 20 indexes each having 250GB of data. Total of 5TB of data approx.

What should be the numbers of

1. Master Nodes with memory size.
2. Data Nodes with memory size.
3. Coordinating Nodes.
4. Shards per each indices.
5. Replica Shards

I had tried with 4 data nodes of 64GB RAM and 5 shards to each index, but the search is to slow.