Why is Redis succeeding?

How reliable is Redis?

Redis is actually a very reliable engine to store data, as long as you keep in mind its design principles. (the Aphyr post is great with that). The replication and cluster modes can add additional complexity (but of course mysql master-slave or master-master have their own risks and complexity as well.)

What is unique about Redis?

Redis has database capabilities. Even when combined with caches' advantages, it performs remarkably well. In fact, if we don't want persistence, it can be turned off for solely using it to cache, temporarily. Redis displays much of its performance to the point that the data always resides in-memory.

Why Redis is faster than database?

Redis stores everything in primary memory. RDBMS stores everything in secondary memory. In Redis, Read and Write operations are extremely fast because of storing data in primary memory. In RDBMS, Read and Write operations are slow because of storing data in secondary memory.

Why Redis is better than memcache?

When storing data, Redis stores data as specific data types, whereas Memcached only stores data as strings. Because of this, Redis can change data in place without having to re-upload the entire data value. This reduces network overhead.