Performance Evaluation of the Interleaved Parity-Check Intra-Disk Redundancy Scheme

This report considers the interleaved parity-check intra-disk redundancy scheme proposed in [1], [2] to enhance the reliability of RAID systems. This scheme aims to protect the system against media-related unrecoverable errors. A detailed performance analysis of this as well as of traditional redundancy schemes based on Reed–Solomon codes and single-parity-check codes is conducted by analytical means. A new model is developed to capture the effect of correlated unrecoverable sector errors. The probability of an unrecoverable failure associated with these schemes is derived for the new correlated model as well as for the simpler independent error model. Furthermore, we derive closed-formexpressions for themean time to data loss of RAID 5 and RAID 6 systems in the presence of unrecoverable errors and disk failures. We then combine these results for a comprehensive characterization of the reliability of RAID systems that incorporate the proposed intradisk redundancy scheme. The impact on the mean time to data loss of a RAID 5 and RAID 6 systems is demonstrated.

[1] A. Dholakia et al., ACM SIGMETRICS Performance Eval. Rev. 34(1) 373-374 (2006).
[2] A. Dholakia et al., IBM Research Report RZ 3652, March 16, 2006.

By: Ilias Iliadis

Published in: RZ3677 in 2006


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