Engines and Versions
Amazon ElastiCache supports these cache engines: Memcached and Redis. Each engine provides some advantages. Use the information in this topic to help you choose the engine and version that best meets your requirements.
After you create a cache cluster or replication group, you can upgrade to a newer engine version (see Upgrading Engine Versions), but you cannot downgrade to an older engine version. If you want to use an older engine version, you must delete the existing cache cluster or replication group and create it anew with the earlier engine version.