Performance Analysis of \ Content - Aware " Load BalancingStrategy FLEX : Two Case

FLEX is a new cost eeective, \locality aware" load balancing solution for a shared web hosting service implemented on a cluster of machines 3]. FLEX allocates hosted web sites to diierent 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 beneets of the new solution. We compare the performance of FLEX against Round-Robin and Optimal strategy. FLEX signiicantly 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. 1 Introduction Demand for Web hosting and e-commerce services continues to grow at a rapid pace. In Web content host-ing, providers who have a large amount of resources (for example, bandwidth, disks, processors, memory, etc.) store and provide Web access to documents for institutions , companies and individuals who lack the resources, or the expertise to maintain a Web server, or are looking for a cost eecient, \no hassle" solution. The shared hosting market targets small and medium size businesses. It is a robust, high volume, low-unit cost business. The most common purpose of a shared hosting Web site is marketing. In this case, many diierent sites are hosted on the same hardware. A shared Web hosting service creates a set of virtual servers on the same server. This supports the illusion that each host has its own web server, when in reality, multiple \logical hosts" share