Redis versus Memcached
ElastiCache supports both Redis version 2.8 onward and Memcached 1.4 onward. These two database engines both support caching operations, but how they do that and what features they support differs. Let's start by looking at Redis.
Redis
Redis can be used as both a caching database and a non-durable data store due to its ability to store key-value pairs in a similar manner to other NoSQL databases. Redis also offers a wide range of features that NoSQL databases typically support, such as sharding, read replicas, and backups.
Read replicas are nodes that are only able to handle read operations. A primary node can handle both reads and writes. Redis uses a system called a shard, which contains one primary node and up to five read replicas. Redis can create up to 500 shards when running in cluster mode. In non-cluster mode (or with cluster mode disabled), Redis will create a single shard. The main benefit to running with cluster mode disabled is that...
