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Modelling Correlated Failures in Redundant Array of Independent Disks in Data Storage Systems

Tahzibi, Mohammad Reza | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 47629 (19)
  4. University: Sharif University of Technology
  5. Department: Computer Engineering
  6. Advisor(s): Asadi, Hossein
  7. Abstract:
  8. With ever increasing amount of digital data, numerous efforts have been made in recent years towards improving reliability and availability of data storage systems. Previous studies have reported significant gap between estimated failure rates and observed failure rates in the field. This gap is mainly due to neglecting correlated failures in Redundant Array of Independent Disks (RAIDs). Proposing a model to consider correlated failures can significantly improve reliability models. In this thesis, we present a reliability model which considers correlated failures in RAID arrays. In the propose model, we use a correlation probability to take into account the correlation of failures between different disks of an array. To this end, we propose a four-state heterogeneous Markov model to estimate the reliability of a conventional RAID array. Unlike previous Markov models, we use a variable failure rate in the proposed Markov model. Experimental results show that the proposed model has less than 5% error compared to field results where the state-of-the-art studies have more than 25% error in the estimation. The correlated failure probability for 8-, 14-, and 24-disk array is equal to 0.05, 0.09, and 0.11, respectively
  9. Keywords:
  10. Redundant Array of Independent Disks (RAID) ; Availability ; Data Storage ; Correlated Failures ; Heterogeneous Markov Model

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