This paper deals with multiprocessor systems required to provide both high performance and good figures of dependability attributes. Fault tolerance is pursued through a proper combination and integration of a diagnostic mechanism, called α count, with simple instances of redundancy-based error processing structures. The resulting fault tolerance strategies are then evaluated through a stochast...

The analysis of performability for large and complex computer systems during design phase, although difficult, is an important activity which contributes to reducing lead times. A pre-requisite of analysis is modelling and a decomposition technique is described. This technique enables the designer to divide the system’s function successively into smaller sub-functions and to treat each sub-func...

We consider multiple class G-networks of processor sharing queues with negative customers which destroy all the customers in a queue. We prove that these networks have a product form solution for steady-state distribution. These networks may have some applications in reliability or performability as the negative customers may clearly model breakdown of computer or communication systems. We also...

The preservation of digital objects is a topic of prominent importance for archives and digital libraries. This paper focuses on the problem of preserving the performability of tasks on digital objects. It formalizes the problem in terms of Horn Rules and details the required inference services. The proposed framework and methodology is more expressive and flexible than previous attempts as it ...

When reconnguring distributed systems, either because failures and/or repairs have occurred, or because the workload requirements have changed over time, an alternative connguration has to be selected, thereby taking performability and costs, i.e., quality of service, requirements into consideration. In this paper we will present the use of Markov-decision models to decide upon such reconngurat...

Service provisioning mechanisms implemented across 5G infrastructures take broadly into use the network service chain concept. Typically, it is coupled with Network Function Virtualization (NFV) paradigm, and consists in defining a pre-determined path traversed by set of softwarized nodes to provide specific services. A well known chain-like framework IP Multimedia Subsystem (IMS), key infrastr...

This note describes the new features of the performance evaluation tool CASPA, which has been extended by algorithms for the model checking of stochastic systems. CASPA uses stochastic process algebras as its input language. Multi-terminal binary decision diagrams (MTBDD) are employed to represent the transition system underlying a given process algebraic specification. The specification of per...

Exceptions constitute a widely accepted fault tolerance mechanism, suitable to manage both hardware and software faults. In performability analysis it is a common practice to exploit software tools capable of describing a system using models expressed in various formalisms. Often these tools provide extensibility features that allow augmenting the primitives of a given formalism, but in most ca...

In this paper jump transitions for the fluid model part in second order fluid stochastic Petri nets (FSPNs) are introduced. The extended formalism is defined, and the underlying partial differential equations are derived. With a jump a certain amount of fluid is added to a fluid place or taken out at once. This amount, the jump height, is sampled from a probability distribution. The dynamics of...