Probabilistic model checking for the Grid and on the Grid Marta Kwiatkowska School of Computer Science, University of Birmingham www.cs.bham.ac.uk/~mzk The increasing dependence of society on computer systems, from desktops through handheld devices to grid systems, deployed in business-critical domains requires assurances of software correctness and performability. Formal verification techniques such as model checking have proved very successful in this area. Model checking involves the construction of a model of a real-life system, formal specification of system’s properties, and then an automated exhaustive analysis of the model. There are many examples of real-life systems for which an accurate analysis must also take into account stochastic aspects of the system’s behaviour, for example randomisation used as a symmetry breaker, uncertainty in user behaviour, or unknown communication delays. Probabilistic model checking [2,3], and in particular the probabilistic model checker PRISM [4,1], have proved very successful in discovering design flaws and performance characteristics of a range of real-world examples [5]. In common with conventional model checking techniques, probabilistic model checking suffers from state-space explosion and therefore extending the range of systems that can be efficiently modelled and analysed is a major challenge. The aim of this talk is two-fold. Firstly, we will demonstrate the usefulness of probabilistic model checking for Grid systems by giving examples of performability studies of computer clusters. Secondly, we demonstrate how probabilistic model checking can be enhanced through the application of parallel computing [6] and, in particular, Grid computing [7]. Finally, we will summarise the main challenges facing this area. 1. 2. 3. 4. 5. 6. 7. PRISM website www/cs.bham.ac.uk/~dxp/prism/. J. Rutten, M. Kwiatkowska, G. Norman and D. Parker, Mathematical Techniques for Analyzing Concurrent and Probabilistic Systems, CRM Monograph Series, vol. 23, AMS, 2004. M. Kwiatkowska, Model Checking for Probability and Time: From Theory to Practice. Invited paper, In Proc. LICS'03, p 351-360, IEEE Computer Society Press, 2003. M. Kwiatkowska, G. Norman and D. Parker, PRISM 2.0: A Tool for Probabilistic Model Checking. In Proc. QEST'04, pages 322-323, IEEE Computer Society Press, 2004. M. Kwiatkowska, G. Norman and D. Parker, Probabilistic model checking in practice: Case studies with PRISM. ACM Performance Evaluation Review on Performance and Verification, 32(4), p 16-21, 2005. Y. Zhang, D. Parker and M. Kwiatkowska, A Wavefront Parallelisation of CTMC Solution using MTBDDs. In Proc. Dependable Systems and Networks (DSN'05). To appear. Y. Zhang, D. Parker and M. Kwiatkowska, Grid-enabled Probabilistic Model Checking with PRISM. In Proc. All Hands Meeting (AHM'05). To appear.