Piecewise estimation of the performability of computer systems

The main objective of the paper is to find acceptable practical methods for evaluating the performability of computer systems. Since the exact evaluation of the performability of such systems becomes intractable as the system grows in dimension and complexity, emphasis is placed on a piecewise estimation that can be obtained with a proposed new numerical procedure. The new numerical procedure is based on randomisation technique which yields a piecewise estimation of the performability (using a Markov reward model) of computer systems. The criteria for choosing a simplified reward structure is addressed and the accuracy of the method is discussed