Rapid read protection in Cassandra 2.0.2

Rapid Read Protection (RRP) in Cassandra allows the system to tolerate node failure without dropping a single request. It was designed for version 2.0 and will be included in the upcoming release of Cassandra 2.0.2. RRP monitors outstanding requests and sends redundant requests to other replicas when the original is slower than expected, improving system resilience and reducing latency variance. By default, it uses a 99th percentile setting for retry configuration, which balances between not performing too many extra requests while still addressing worst-case problems.