Performance of Two-Disk Failure-Tolerant Disk Arrays
IEEE Transactions on Computers
Higher reliability redundant disk arrays: Organization, operation, and coding
ACM Transactions on Storage (TOS)
Why specialized disks for composite operations may be unnecessary
ACM SIGARCH Computer Architecture News
RAID level selection for heterogeneous disk arrays
Cluster Computing
Rebuild processing in RAID5 with emphasis on the supplementary parity augmentation method[37]
ACM SIGARCH Computer Architecture News
Hierarchical RAID: Design, performance, reliability, and recovery
Journal of Parallel and Distributed Computing
The comprehensive performance analysis of striped disk array organizations - RAID-0
Proceedings of the 2013 International Conference on Information Systems and Design of Communication
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RAID5 tolerates single disk failures by exclusive-ORing (XORing) the blocks corresponding to a requested block on the failed disk to reconstruct it. This results in increased loads on surviving disks and degraded disk response times with respect to normal mode operation. Provided a spare disk is available, a rebuild process systematically reads successive disk tracks, XORs them to recreate lost tracks and writes them onto a spare disk, thus returning the system to its original state. Rebuild time is important since RAID5 disk arrays with a single disk failure are susceptible to data loss if a second disk fails. According to the vacationing server model (VSM), rebuild read requests on surviving disks are given a lower priority than external user requests, so as to have less impact on their response time. Given that disk loads are balanced due to striping, rebuild time can be approximated by the time to read the contents of any one of the surviving disks. The analysis of the M/G/1 queueing model of VSM, given in this article, is more accurate and yet simpler than a previous analysis, but it also takes into account the effect of disk zoning explicitly. We also present a heuristic method to estimate rebuild time, which can be combined with the new analysis. The ability to quickly and accurately estimate rebuild time is useful in computing the reliability of RAID5 systems, especially during design tradeoff studies. The accuracy of the various analyses to estimate rebuild time are checked against detailed simulation results.