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Availability of enterprise IT systems: an expert-based Bayesian framework

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Abstract

Ensuring the availability of enterprise IT systems is a challenging task. The factors that can bring systems down are numerous, and their impact on various system architectures is difficult to predict. At the same time, maintaining high availability is crucial in many applications, ranging from control systems in the electric power grid, over electronic trading systems on the stock market to specialized command and control systems for military and civilian purposes. This paper describes a Bayesian decision support model, designed to help enterprise IT system decision-makers evaluate the consequences of their decisions by analyzing various scenarios. The model is based on expert elicitation from 50 experts on IT systems availability, obtained through an electronic survey. The Bayesian model uses a leaky Noisy-OR method to weigh together the expert opinions on 16 factors affecting systems availability. Using this model, the effect of changes to a system can be estimated beforehand, providing decision support for improvement of enterprise IT systems availability. The Bayesian model thus obtained is then integrated within a standard, reliability block diagram-style, mathematical model for assessing availability on the architecture level. In this model, the IT systems play the role of building blocks. The overall assessment framework thus addresses measures to ensure high availability both on the level of individual systems and on the level of the entire enterprise architecture. Examples are presented to illustrate how the framework can be used by practitioners aiming to ensure high availability.

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Acknowledgments

The authors are grateful to those colleagues and respondents who helped improving the survey before it was sent out, as well as to all the researchers who responded when invited. A special thanks is due to Lars Nordström for his contribution and support throughout the project. Three anonymous reviewers provided useful comments upon the paper. A previous version of this paper was presented at the Workshop on Software Quality and Maintainability (SQM 2010)—Franke et al. (2010)—and the authors would also like to thank the anonymous reviewers of that version for their comments.

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Authors and Affiliations

  1. Industrial Information and Control Systems, Royal Institute of Technology, Stockholm, Sweden

    Ulrik Franke, Pontus Johnson, Johan König & Liv Marcks von Würtemberg

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  1. Ulrik Franke
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  2. Pontus Johnson
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  3. Johan König
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  4. Liv Marcks von Würtemberg
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Correspondence to Ulrik Franke.

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Franke, U., Johnson, P., König, J. et al. Availability of enterprise IT systems: an expert-based Bayesian framework. Software Qual J 20, 369–394 (2012). https://doi.org/10.1007/s11219-011-9141-z

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