A Performance Model of Mixed-Workload Multimedia Information Servers

Advanced multimedia applications such as digital libraries or teleteaching exhibit a mixed workload with accesses to both "continuous" data (e.g., video) and conventional, "discrete" data (e.g., text/image documents). As the fractions of continuous-data versus discrete-data requests vary over time, we consider a multimedia storage server with both classes of data spread across all disks for dynamic load sharing. This paper develops a stochastic model for predicting the performance of mixed multimedia workloads on a given system configuration. It focuses on analyzing the response-time distribution for discrete-data requests under potential contention with continuous-data requests. We derive an upper bound for the probability that the response time of a discrete-data request exceeds a specified tolerance threshold. Experimental results from detailed simulation studies demonstrate the high accuracy of the analytical model. Thus the model is an appropriate basis for server capacity plannin...