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

J. Patel and O. Das (Canada)

Keywords

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

Abstract

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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