Performability analysis of guarded-operation duration: a successive model-translation approach

When making an engineering design decision, it is often necessary to consider its implications on both system performance and dependability. We present a performability study that analyzes the guarded operation duration for onboard software upgrading. In particular, we define a "performability index" Y that quantifies the extent to which the guarded operation with a duration /spl phi/ reduces the expected total performance degradation. In order to solve for Y, we progressively translate its formulation until it becomes an aggregate of constituent measures conducive to efficient reward model solutions. Based on the reward-mapping-enabled intermediate model, we specify reward structures in the composite base model which is built on three stochastic activity network reward models. We describe the model-translation approach and show its feasibility for design-oriented performability modeling.