Stochastic performance guarantees for mixed workloads in a multimedia information system

We present an approach to stochastic performance guarantees for multimedia servers with mixed workloads. Advanced multimedia applications such as digital libraries or teleteaching exhibit a mixed workload with accesses to both "continuous" and conventional, "discrete" data, where the fractions of continuous data and discrete data requests vary over time. We assume that a server shares all disks among continuous and discrete data, and we develop a stochastic performance model for the resulting mixed workload, using a combination of analytic and simulation based modeling. Based on this model we devise a round based scheduling scheme with stochastic performance guarantees: for continous data requests, we bound the probability that "glitches" occur and for discrete data requests, we bound the probability that the response time exceeds a certain tolerance threshold. We present early results of simulation studies.