Request distribution-aware caching in cluster-based Web servers

This work presents a performance analysis of request distribution-aware caching in cluster-based Web servers. We use the Zipf-like request distribution curve to guide static Web document caching. A combination of cooperative caching and exclusive caching provides for a cluster-wide caching system that avoids document replication accross the cluster. We explore the benefits of cooperative caching algorithms that use request distribution information to steer their behavior over general purpose cooperative caching algorithms. Exclusive caching exercises a fine-grained control over replication of data blocks across the cluster. The performance of the system has been assessed by using the WebStone benchmark. Our cluster-based server employs Linux kernel-level implementations of cooperative caching and exclusive caching. Current results show that request distribution-aware caching outperforms general-purpose caching algorithms, makes up for the performance loss of non-replicated data solutions and compares favorably to fully-replicated solutions.