># Performance is better because data is accessed from memory instead of through a database to a disk.
># Scalability is linear because as more servers are added data is transparently load balanced across the servers so there is an automated in-memory sharding.
># Availability is higher because multiple copies of data are kept in memory and the entire system reroutes on failure.
># Application development is faster because there’s only one layer of software to deal with, the cache, and its API is simple. All the complexity is hidden from the programmer which means all a developer has to do is get >and put data.
All but the first thing apply to disk based databases too... At least the new ones like Cassandra, as well as the old ones with the right packages.