Dependability evaluation using UltraSAN

William H. Sanders, W. Douglas Obal

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Dependability evaluation is an important, but difficult, aspect of the design of fault-tolerant computer systems. This software demonstration highlights UltraSAN, a stochastic activity network-based package for model-based performance, dependability, and performability evaluation of such systems. The package supports solution by both simulation-based and analytic methods. Of particular importance in the evaluation of dependable systems by analytic means in the control of an often explosive state space growth. UltraSAN has the potential to do this, using recently developed reduced base model construction techniques which exploit symmetries inherent in the SAN structure during construction of the underlying stochastic process representation. Four analytic solvers are available: SOR and LU decomposition for steady-state variables, and uniformization for transparent instant-of-time and interval-of-time variables. For models with characteristics that preclude analytic solution, transient and steady-state simulation can be used. This demonstration illustrates the use of UltraSAN and reduced base model construction by considering the evaluation of a fault-tolerant distributed system. Model generation via an X Windows based graphical interface, stochastic process construction, and model solution, using numerical methods, are illustrated.

Original languageEnglish (US)
Title of host publicationDigest of Papers - International Symposium on Fault-Tolerant Computing
Editors Anon
PublisherPubl by IEEE
Number of pages6
ISBN (Print)0818636823
StatePublished - 1993
Externally publishedYes
EventProceedings of the 23rd International Symposium on Fault-Tolerant Computing - Toulouse, Fr
Duration: Jun 22 1993Jun 24 1993

Publication series

NameDigest of Papers - International Symposium on Fault-Tolerant Computing
ISSN (Print)0731-3071


OtherProceedings of the 23rd International Symposium on Fault-Tolerant Computing
CityToulouse, Fr

ASJC Scopus subject areas

  • Hardware and Architecture


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