Assuring QoS differentiation and load balancing on web servers clusters

The number of users of services deployed on the Internet has been increasing continually. This has been causing overload in a great amount of Web servers reducing QoS (quality of service) offered by service providers. Furthermore, users with different QoS aspirations have been forced to share available processing resources in a same way even they can pay more. To deal with these problems, a possible solution is the balancing of imposed load among a certain number of computers to improve performance and the use of admission control mechanisms to allow differentiated allocation of resources for specific service classes. This paper presents WS-DSAC (Web servers ifferentiated services admission control), a diffserv-based admission control and load balancing mechanism conceived to improve QoS on Web servers clusters. WS-DSAC has three main aims: to balance the imposed load, to guarantee different QoS levels and to use available resources in an effective way. We also present evaluation experiments showing the mechanism is able to achieve these objectives