What happens to Redis-cached data when its container restarts, and how would you change that behavior?

By default, Redis is an in-memory store; without persistence configured, all data is lost on restart since nothing was ever written to disk. To survive restarts, you'd enable RDB snapshotting or AOF (append-only file) persistence and mount a named volume at Redis's data directory, so the persisted file survives container recreation — though for pure caching use cases, this loss-on-restart behavior is often acceptable and even desirable.