Performance analysis of "content-aware" load balancing strategy FLEX: two case studies

FLEX is a new cost effective, locality aware load balancing solution for a shared Web hosting service implemented on a cluster of machines (Cherkasova, 2000). FLEX allocates hosted Web sites to different machines in the cluster based on the sites' processing and memory requirements which are estimated using the site logs. Appropriate routing of requests can be achieved by using the DNS infrastructure, since each hosted Web site has a unique domain name. Using a simulation based on real traces, we evaluate the potential benefits of the new solution. We compare the performance of FLEX against Round-Robin and Optimal strategy. FLEX significantly outperforms Round-Robin (up to 110-250% in average server throughput), getting within 8%-30% of optimal performance achievable for those traces. FLEX solution shows superliner speedup when the number of nodes is increased from four to eight because it takes advantage of both the doubled processing power and memory.