This document discusses choosing the appropriate Amazon EC2 instance types for Cassandra workloads. It emphasizes that one size does not fit all, and the instance must be tailored to the specific workload in terms of reads vs writes and CPU vs memory needs. It reviews the storage options of EBS volumes and ephemeral storage, noting the better performance of ephemeral. It then provides examples of suitable instance types for different Cassandra workload volumes, from development and light production to real heavy production use cases.