Why not? It has a WAL persisted to disk at a desired interval. It provides the same durability levels of most databases.

http://redis.io/topics/persistence

Let me be clear, I think redis is a well engineered piece of software and I have been constantly impressed with the way antirez runs the project.

Specifically for the question of a locking service, I need more availability than what a single node can offer. I'm not sure if you are advocating for using redis cluster as a locking service, but since it intentionally doesn't offer write safety during a partition that does not seem advisable.