Redis keeps the dataset in memory but writes to disk asynchronously and reloaded when Redis is restarted. Or the data can be saved each time a command is issued or on schedule to minimize data loss.
Redis also has master-slave replication and setup consists of a 'slave of x.x.x.x' line in the slave's config file. And is the only trivial thing about Redis.
The Command Reference shows a lot of thought and hard work has gone into Redis. Redis has a lot to offer Joe Average DBA without making him forsake his comfortable base.
- SQL is not going away. And not like COBOL, FORTRAN or I Love Lucy not going away. SQL solves too many problems to be pushed aside. It does have limitations but cleaver engineering will mitigate them.