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 o...

Compact symbolic representations of large labelled transition systems, based on binary decision diagrams (BDD), are discussed. Extensions of BDDs are considered, in order to represent stochastic transition systems for performability analysis. We introduce Decision Node BDDs, a novel stochastic extension of BDDs which preserves the structure and properties of purely functional BDDs. It is shown ...

Several recent studies have reported the phenomenon of software aging, where the state of the system degrades with time due to exhaustion of operating system resources, data corruption and numerical error accumulation. This eventually leads to performance degradation or crash/hang failure of the software. In this paper, we propose a measurement-based performability model to estimate the rate of...

Musical composers frequently make use of new technologies in instrumentation. Whilst orchestral traditions remain strong and the instruments viable, what of the works of composers of electronic music where the sound sources have fallen into disrepair, obsolescence, or modern technology has changed the sound so that it bears no relation to the original? Beyond collections of manuscripts and reco...

MDWNsolver is a framework for system modeling and optimization of performability measures based on Markov Decision Petri Net (MDPN) and Markov Decision Well-formed Net (MDWN) formalisms, two Petri Net extensions for high level specification of Markov Decision Processes (MDP). It is integrated in the GreatSPN suite which provides a GUI to design MDPN/MDWN models. From the analysis point of view,...

Increasingly, fault-tolerant distributed software applications use a separate architecture for failure detection instead of coding the mechanisms inside the application itself. Such a structure removes the intricacies of the failure detection mechanisms from the application, and avoids repeating them in every program. However, successful system reconfiguration now depends on the management arch...

In this paper we develop a variant of a previously proposed method (the regenerative randomization method) for the transient analysis of dependability/performability models. The variant is obtained by developing a closed-form expression for the solution of the truncated transformed model obtained in regenerative randomization and using a Laplace transform inversion algorithm. Using models of mo...