In AWS ElastiCache, when I'm creating a REDIS cluster, the number of nodes option text box is disabled with a fixed '1' and same goes in the cluster admin page for the 'add node' button once it's created.
Is that a limitation of the engine (and they are using the same dialog for memcached) or I am missing something?
Amazon ElastiCache does not support sharding for Redis today and that is the reason the number of nodes is fixed as '1'. However, if you are looking for read scaling you can create multiple read replicas.
Just to make this thread up to date, Amazon recently announced that its ElastiCache service will support sharding for Redis clusters with up to 15 nodes.
Take a look at https://aws.amazon.com/blogs/aws/amazon-elasticache-for-redis-update-sharded-clusters-engine-improvements-and-more/
