A New Model for Evaluating Performability under the Effects of Software Aging and Rejuvenation

J. Patel and O. Das (Canada)


Analytical modelling, fault tolerance, software aging, software rejuvenation, performability


When a fault-tolerant layered distributed system continues its operation despite the presence of component failures, its performance is usually degraded. Its performance can also be degraded if it is executing continuously for a long period of time due to a phenomenon known as Software Aging. To prevent unexpected or unplanned outages due to aging, a pro-active technique called software rejuvenation can be employed. This technique involves gracefully terminating an application and immediately restarting it with a refreshed internal state. For proper modeling of these systems, their performance and dependability characteristics need to be considered in a unified way, called performability. This paper proposes a model to evaluate the effects of software aging and rejuvenation on performability of these layered systems. Specifically a Layered Queueing Network (LQN) is used for performance analysis and a Multi State Fault Tree (MSFT) is used for dependability analysis.

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