The Study Of Web Server Cluster QoS

The growth of the demand of the network is higher than the development of network itself at present. So it is still unavoidable to deal with delay and denial of service phenomena. This makes end-to-end Quality of Service (QoS) seem more and more important. And end-to-end QoS includes two respects: networks QoS and end-system QoS. With the growth of E-commerce and the increase of HTTP requests, the phenomena of congestion and queueing are more and more serious. So it is imposible to solve the problem of end-to-end QoS control by only depending on networks QoS. And thus Web Server becomes an important part in end-to-end networks. It is necessary to study the QoS mechanisms and policies for it.With the growth of network, high scalability, reliability, availability and efficient cost/performance ratio are strongly required for the network servers. Web server cluster is an economic and effective method that can meet the demand. So Web server cluster QoS is an important respect of offering satisfying Web QoS to users. The papers about it are not many, and let alone the products and patents. This paper regards this as the starting point and main goal.First this paper studies background knowledge and present research state of Web QoS control and the necessarily of studying the Web server cluster QoS. This paper makes the decision that there are mainly two server cluster QoS models: the server cluster QoS model of distributing QoS policy and the server cluster QoS model of mixing QoS policy. And after the comparison of the two models, this paper draws the conclusion that model of distributing QoS policy excels model of mixing QoS policy.And this paper proposes a Web Cluster QoS model in which a distributing-aware heterogeneous realtime policy -DAHRP is realized. This model includes performance monitoring part, admission control part, requests classification part, servers partition part, web adjustment part and requests scheduling part. The key problems have been detailed described in this paper. In the end, this paper makes a simulation on the Web Cluster QoS model using a simulation algorithm that is proposed by oneself. From the comparison's result, it is proved* that DAHRP is better than the others.