PERFORMANCE PREDICTIONS FOR THE UPGRADING OF A VAX-CLUSTER

During the last two decades many interesting and useful results have been obtained in the area of queueing networks. It has been shown that the queueing network model is a powerful tool in computer perfonnance analysis. In this paper we report on some of the difficulties we met in a perfonnance study for the upgrading of the VAX-cluster at the Eindhoven University of Technol-ogy. Our conclusion has to be that there are sufficiently many queueing network models and techniques for analyzing them, but that for accurate perfonnance predictions the behaviour of memory contention is not well understood. 1. INTRODUCTION. At the Eindhoven University of Technology (EUT) an attempt has been made to model and analyse the perfonnance of the local VAXNMS (or shortly VAX) cluster, consisting of three VAXes sharing background memory. The result is a computer package called VAMP (VAX Analysis and Measurement Package), consisting of the following S programs (cf. [2,3])