Understanding service demand for adaptive allocation of distributed resources

Internet services experience frequent changes in demand, resource characteristics and service requirements. A service can meet its requirements with minimal cost only if the allocation of its distributed resources can be adaptively controlled. The design of adaptive control schemes requires a solid understanding of the dynamic characteristics of the distributed service, demand and resources. This study examines the dynamic properties of distributed demand and differs from prior demand characterization work by focusing on dynamic variations across clients, time and region which are crucial in adaptively allocating distributed resources. Our analysis of the demand for the 1998 World Cup web site finds that the dynamic behavior of a small subset of clients is representative of the entire demand, the churn in the active set of clients from day to day is relatively small and that regional demand shows significant, and predictable, variations in the hourly scales. These results will provide guidance for the design of adaptive policies.