APPARATUS AND METHOD FOR EVALUATING AND PREDICTING COMPUTER I/O PERFORMANCE USING I/O WORKLOAD SNAPSHOTS FOR MODEL INPUT

A method of evaluating and predicting the performance of an I/O disk system comprised of one or more disk controllers and cooperating disk units using a simulation model containing a stact constructed such that delays are formulated as sets of stochastic processes. The simulation model includes at least one statistical submodel and has delay parameters which are settable in accordance with a selectable I/O disk configuration. The simulation model is driven by a selectable I/O workload snapshot grouped into I/O batches. The simulation model provides both overall and batch output data in response to the I/O workload snapshot. Provision is also made for the simulation model to take into account the presence of cache storage in the selected I/O configuration.