A new approach to performance modelling of Client/Server distributed data base architectures

The recent technological advances in the field of computer and communication lead to distributed data base (DDB) architectures based on the Client/Server paradigm. Available DDB performance prediction methodologies are not sufficiently adequate being too expensive both in the model definition and in the model analysis because of the structural complexity and the large system dimension. This paper concentrates on a new approach to performance modeling of DDB systems called ''independent modelling approach''. This approach separates the DDB software model from the DDB machinery model, and models from solution techniques. This way the aspects related to data contention can be analysed as a pure software characteristic and separated from resource contention, considered as a machinery characteristic. Furthermore, it is possible to analytically model some system aspects (e.g., the software only, or part of it, without involving the machinery model), and apply combined analytical/simulation methods for the remaining system aspects. This results in higher flexibility at lower computational cost in the performance analysis of complex DDB architectures. A case study is developed and experimental results are discussed to show the effectiveness of the approach.