As a rule of thumb, for Scylla’s best performance, each client needs at least 1-3 connections per Scylla core. For example, in a cluster with three nodes, each node with 16 cores, each client application should open 32 (2x16) connections to each Scylla node.
Additional Resources:
- How to Write Better Apps lesson on ScyllaDB University
- Maximizing Performance via Concurrency While Minimizing Timeouts in Distributed Databases blog post
- Best Practices for ScyllaDB Applications blog post