A repair time model of a web based system including administrator working hours

• Autorzy: Walkowiak T.
• Języki publikacji: EN

Abstrakty

EN

The paper presents a web based system reliability analysis. We propose to model different types of faults (hardware one, software and security incidents) taking consideration only the effect of the failure, not the source of the fault. It is assumed that failure events are independent and the time to failure is exponential. Whereas the time to repair is not exponential since repair actions are taken only when administrators are at work. We assume that administrators are not working 24/7. The paper presents an algorithmic model of the repair time including administrator working hours. The model is used to estimate reliability parameters (mean time, standard deviation and 90th percentile of yearly down time) by a use of Monte-Carlo simulation. The numerical results are compared with results from the analytical model (Markov one) that assumes exponential distribution of all repair times. Results for two web exemplar web systems (with reliability model consisting of two and five states) show the range of error caused by the exponential distribution assumption.

Słowa kluczowe

EN

reliability; web based system; repair time; working hours

• Wydawca: Polskie Towarzystwo Bezpieczeństwa i Niezawodności
• Czasopismo: Journal of Polish Safety and Reliability Association
• Rocznik: 2016
• Tom: Vol. 7, No. 1
• Strony: 233--240
• Opis fizyczny: Bibliogr. 9 poz., rys., tab., wykr.

Twórcy

autor

Walkowiak T.

• Wroclaw University of Science and Technology, Faculty of Electronics, Poland

Bibliografia

• [1] Aven, T. & Uwe, J. (1999). Stochastic Models in Reliability. New York: Springer.
• [2] Barlow, R. & Proschan, F. (1996). Mathematical Theory of Reliability. Society for Industrial and Applied Mathematics, Philadelphia.
• [3] Caban, D. & Walkowiak, T. (2012). Preserving continuity of services exposed to security incidents. Proc. The Sixth International Conference on Emerging Security Information, Systems and Technologies, SECURWARE 2012, IARIA, 72-78.
• [4] Fishman, G. (1996). Monte Carlo: Concepts, Algorithms, and Applications. Springer-Verlag.
• [5] Jia, J. & Wu, S. (2009). A replacement policy for a repairable system with its repairman having multiple vacations. Computers & Industrial Engineering 57, 1, 156-160.
• [6] Walkowiak, T. (2014). Simulation based availability assessment of services provided by web applications with realistic repair time. Eksploatacja i Niezawodność – Maintenance and Reliability 16, 2, 341-346.
• [7] Walkowiak, T. (2014). Weekly availability changes of web applications implemented in virtualized environment. Nowakowski, T. et al. Safety and Reliability: Methodology and Applications, CRC Press.
• [8] Walkowiak, T. & Caban, D. (2015). Improvement of dependability of complex web based systems by service reconfiguration. Dependability Problems of Complex Information Systems. Advances in Intelligent Systems and Computing 307, 149-165.
• [9] Zhang, Y. L. & Wu, S. (2009). Reliability analysis for a k/n(F) system with repairable repair-equipment. Applied Mathematical Modelling 33, 7, 3052-3067.

Uwagi

Opracowanie ze środków MNiSW w ramach umowy 812/P-DUN/2016 na działalność upowszechniającą naukę (zadania 2017).