Good point, but I could add that case 1 is vanishingly unlikely to happen in a real system. You always have hot keys, i.e. a Zipfian distribution. That's almo

Good point, but I could add that case 1 is vanishingly unlikely to happen in a real system. You always have hot keys, i.e. a Zipfian distribution. That's almost tautological for a cache -- by using a small amount of space you can handle most of the reads. So, not knowing much about Redis, I would conclude based on this blog post that memcached has a pretty big advantage as a cache in real systems (multithreading).