ElastiCache is a managed service related to AWS’s in-memory cache.
The cache engine can be selected from Redis and memcached.
There are units of nodes, shards, and clusters.
Node
– cache server
– the smallest unit of ElastiCache
– The performance(memory, CPU, etc.) varies depending on the selected node type.
Sharde
– A group that organizes nodes
– One shard has one primary node(read / write) and 0-5 read replicas (read only)
Cluster
– A group that organizes shards
– A cache engine can be selected for each cluster. Cluster mode can be enabled or disabled.
