Stochastic Modeling Formalisms for Dependability, Performance and Performability

In this chapter, we discuss practical issues regarding analytical modeling of complex computer systems. We compare diierent model types in terms of their strengths and weaknesses for model construction, eeciency and accuracy of solution algorithms and the desired performance measures. The basic concepts of performance, dependability and performability modeling are introduced using the example of a multipro-cessor system. With respect to combined modeling of performance and dependability two major problems are identiied, largeness and stiiness, and a variety of approaches to deal with them are presented. Finally, techniques for high level model speciication are brieey reviewed.