In this tutorial, we discuss several practical issues regarding speci cation and solution of dependability and performability models. We compare model types with and without rewards. Continuous-time Markov chains (CTMCs) are compared with (continuous-time) Markov reward models (MRMs) and generalized stochastic Petri nets (GSPNs) are compared with stochastic reward nets (SRNs). It is shown that ...

In this paper second order uid stochastic Petri nets (FSPNs) will be used for modelling reward in a performability model. Two variations of the performability model are presented. In the rst one two uid places are used, one of which represents the proot (reward) obtained by operating the system and the other one the buuer, that is approximated continuously. In the second model only one uid plac...

Optimizing the performance and availability of an IT service in the design stage are typically considered as independent tasks. However, since both aspects are related to one another, these activities could be combined by applying performability models, in which both the performance and the availability of a service can be more accurately predicted. In this paper, a design optimization problem ...

Meyer, J.F,, Performability: a retrospective and some pointers to the future, Performance Evaluation 14 (1992) 139-156. As computing and communication systems become physically and logically more complex, their evaluation calls for continued innovation with regard to measure definition, model construction/solution, and tool development. In particular, the performance of such systems is often de...

This paper deals with object-oriented real-time dependable systems required to achieve the best usage of the resources even under adverse circumstances as transient overloads or component failures. Various possible tradeoffs among the different application requirements must be considered to allow a flexible management of system resources. On the basis of a simple formulation of the concept of o...

This paper describes how MEADEP, a system level dependability prediction tool, and CASRE, a software reliability growth prediction tool can be used together to predict system reliability (probability of failure in a given time interval), availability (proportion of time service is available), and performability (reward-weighted availability) for a. The system includes COTS hardware, COTS softwa...

We present the Stochastic Petri Net Package (SPNP), a versatile modeling tool for performance, dependability, and performability analysis of complex systems. Input models developed based on the theory of stochastic reward nets are solved by e cient and numerically stable algorithms. Steady-state, transient, cumulative transient, time-averaged, and \up-to-absorption" measures can be computed. Pa...

The problem of computing performability probabilities in stochastic PERT and ow networks is studied when the network is \minimally designed" to withstand any two component failures. Polynomial-time algorithms to compute performability when the network is planar| the nonplanar versions being NP-hard | solve related \two-path subset" problems. Given an acyclic graph with weights on the arcs, the ...

Exactly computing network reliability and performability measures are NP-hard problems, precluding their frequent use in design of large networks. Instead, Monte Carlo simulation has been frequently used by network designers to obtain accurate estimates. This paper focuses on simulation estimation of network reliability and performability. First, a literature survey of existing approaches is gi...