valkey

For a new Amazon ElastiCache cluster in 2026, Valkey is the sensible default engine. It keeps the Redis OSS data model and commands, AWS prices it lowest, and new ElastiCache features such as durability arrive only on Valkey. Memcached still fits one narrow job well: a simple, multithreaded object cache that grows and shrinks by adding or removing nodes. Redis OSS mostly makes sense for an existing cluster that is not ready to move yet.

An introduction to the public MemoryDB test project: why it needs its own harness, what the repository is building, and what a documented run must contain. The repository is still a scaffold. No MemoryDB benchmark results are presented here.

Nine Valkey 9.0 runs compare ElastiCache R5, R6g, and R7g: zero evictions, 27.1-33.6% headroom, an R5 lead, and overlapping Graviton results.

Nine fixed-workload Valkey 9.0 runs across ElastiCache M5, M6g, and M7g show overlapping performance ranges, nearly identical key capacity, and no simple generational improvement ladder.

Nine Valkey 9.0 runs across ElastiCache M7g, R7g, and C7gn reveal a hidden test variable: memtier keyspace scales with node memory, so equal workers and duration do not create a fixed-workload comparison.