HP Labs Technical Reports
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Performance Analysis of Scalable Web Hosting Service with FLEX: Two Case Studies
Cherkasova, Ludmila; DeSouza, Mohan; Ponnekanti, Shankar
Keyword(s): web hosting service; web server cluster; load balancing; scalability; super linear speedup; performance analysis
Abstract: FLEX is a new cost effective, "locality aware" load balancing solution for a shared web hosting service implemented on a cluster of machines [C99]. 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. FLEX is simple, inexpensive and can be easily implemented on top of the current infrastructure used by Web hosting service providers. The performance benefits achieved by FLEX from both load distribution and efficient memory usage make it a viable solution for low-end shared web hosting services. Using two case studies (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 130% in average server throughput), getting within 5%-15% of optimal performance achievable for those traces. Miss ratio is improved 2-6 times. 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.
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