OpenSESAME: simple but extensive structured availability modeling environment

Traditional modeling tools for high availability systems do not combine intuitivity, efficiency, and modeling power under the same umbrella. For example, combinatorial methods like fault trees or reliability block diagrams are quite intuitive, allow for a stepwise refinement of the models and can be analyzed efficiently. However, their modeling power is limited, as traditional methods for analyzing these models rely on the fact that there are no statistical dependencies between the failure and repair behavior of the components. The work presented here is a contribution towards modeling environments which are both user friendly and possess a high modeling power. It shows how the tool OpenSESAME can be used to design models for highly available systems which on the one hand are as intuitive as traditional reliability block diagrams and on the other hand can be enriched with inter-component dependencies. These dependencies can be added and removed at any time without the necessity of changing the hierarchic structure of the model.