The research of differentiated service and load balancing in Web cluster

Differentiated service, as a key solution to meet the heterogenicity ofWeb clients' QoS requirements, has been widely used to optimize the server utilization without over-providing resources. Based on the relative differentiated service, this paper treats the application of proportional delay as a optimal control problem, and focuses on the cluster-side architecture improvement as well as QoS controller design. A load balancingWeb cluster architecture supported differentiated service is proposed and implemented. By system identification and resource optimal control, the frontend dispatcher could adjust the resource quotas assigned to different classes in every single back-end server, and Multi-class based Maximum Idle First load balancing strategy is designed to ensure a fair resource consumption among back-end nodes. As a result, the end-to-end delay is controlled and proportional delay is guaranteed. The experiments demonstrate that no matter using Round-Robin, Least Connection Scheduling or Maximum Idle First load balancing strategy, the proposed resource optimal controller could hold the relationship among different classes. Compared to Round-Robin and Least Connection First Scheduling, Maximum Idle First strategy increases the cluster throughput by 33% and reduces the average delay by 21%.