The Study On Heterogeneous Web Server Cluster Load Balancing Algorithms

With the development of Internet and the increase of users, the tradition and singularity Web Server cannot satisfy the need of the clients, so how to improve the performance of Web Server has become a hotspot in the Web field. Web Server Cluster is an available technique to resolve the problem. A lot of low performance Web servers are united to a high one. It costs low and may extend based on the primary invest. It adapts to the Web Site that operation scale can't sure or middle and small Web Site update to a great one. It is easy for people to accept, but it must resolve a problem, that is, how to dispatch the load to each Web Server of Cluster evenly.In this paper, many technical data have been referenced and a lot of existing ways have been analyzed, and found that some great Web Site always adopt Load Balancing Technology, that is, a computer receives all HTTP requests and dispatches them to each Web Server with load balancing algorithms. At present, load-balancing algorithms compose Round_Robin, Weight Round_Robin, LCF, FRP and so on. But most of these algorithms are static algorithms, and haven't been optimized, so they aren't adapted to heterogeneous Web Server Cluster.In order to put toward a load balancing algorithm which is adapted to heterogeneous web server cluster, we analyzed the flux characteristic of Web and used a parameter to evaluate the performance of Web Server Cluster桽ystem efficiency. A heterogeneous Web Server Cluster load model is proposed, and a heterogeneous Web Server Cluster load balancing algorithm ALB (Adaptive Load Balancing). Not only the performance difference of Web Server is thought over, but also the content of request.The theory analysis and test result of the algorithms are given in this paper. The result indicates that ALB algorithm can get the shorter mean response time in the same condition, so it is better than the other ones in the paper.