You may also want to look at Membase.
http://www.northscale.com/products/membase_server.html
I have not used it, but it appears to be similar to Redis in that it is a memory-centric KV store with persistence. The major differences from what I can see are:
- Redis has significantly more data manipulation capability (ordered sets, etc.)
- Redis has a pending Redis Cluster project to add horizontal scalability
Redis has a single tier of data offload to disk (VM) based on a hybrid algorithm that considers both LRU and the size of the object.
Membase uses the memcached wire protocol - useful as an upgrade path for existing applications
- Membase is set up to scale horizontally using a distributed hashtable approach
- Membase can support multiple tiers of data offload using an LRU approach (very seldom used goes to disk, somewhat seldom stuff goes to SSD, frequent stuff stays in RAM)
- Not sure about TTL capability in Membase.
The choice may depend on the degree to which your application can leverage the extra data manipulation functionality in Redis.
