A HIERARCHICAL MARKOV RELIABILITY MODEL FOR DATA STORAGE SYSTEMS WITH MEDIA SELF-RECOVERY

摘要

A Redundant Array of Independent Disks (RAID) system with n disks or hard drives can be modeled as a fc-out-of-n repairable system for which at least k operational disks are required. This paper proposes a hierarchical Markov model to estimate the reliability of RAID systems. The method encompasses Markov models for evaluating the reliability of individual disks at the lower level and the redundant model for evaluating the reliability of entire RAID at the system level. Both hardware and media failures are considered, and the media failures can be potentially recovered via the disk self-restoration mechanism. The system mean-time-to-data-loss is also derived and results are compared to those estimated from system-based Markov models. The major contribution of this work is that the reliability for RAID systems is approached by combining the redundant modeling technique with the single disk-based Markov model, thus simplifying the computational efforts. The proposed method is applied on RAID-5 and RAID-6 systems to demonstrate the applicability and performance of the new model.