hence we propose introducing the energyproportional concept the idea that the power consumption of a system should be proportional to its workload to the server cluster by matching the number of active servers to the load we also present the design and implementation of a prototype of the server cluster and evaluate it by examining power usage and response times to some kinds of traffic patterns as a result our scheme reduces power consumption effectively under low load succeeding in saving over energy compared to the conventional management policy where all servers are kept in service whatever the workload without affecting the response time