Adaptive parameter setting for QoS aware load balancing

The switft growth of the Internet has boosted the use of Web based services and in some pratical cases has led to overwhelming request bursts to servers. Relational database queries, image storage/retrieval and other new types of application transactions have become increasingly popular. Their coexistence in commercial parallel and distributed systems have generated soma uniquely new loading problems. For example, the constant increase of request rate finally leads to processing power requirement exceeding that of the accessed server. As a consequence, the response times increase and some portion of the requests are lost. Clustering of servers to meet the growing demand for server processing capacity, especially in web-based service supply, have created the need for intelligent switching at front-end devices. As a consequence of clustering, multilayer switching schemes have been developed to enable optimum loading of the individual servers in a cluster. In this paper, we formulate the load balancing problem taking the QoS into consideration and introduce a QoS aware load balancing algorithm (QoS-LB). The performance of the algorithm is simulated and results indicating the load balancing capacity of the algorithm are presented. The overall idea is to describe an algorithm that actually provides Class of Service based differentiated access to server clusters and offers better playgroung for QoS mechanisms in client-servers environments. The engineering task to offer guarantees with such a differentiation tool is out of the scope of this paper.