Modeling the Endurance Reliability of Intra-disk RAID Solutions for mid-1X TLC NAND Flash Solid State Drives

Ensuring data protection in Solid State Drives (SSD) is vital in enterprise application scenario. However, as the reliability of their storage medium, namely the NAND Flash, is decreasing at the same pace of the technology scaling, this activity is becoming non-trivial. The evaluation of different recovery strategies that employ both complex Error Correction Codes and second level error correction is becoming a de facto. In this paper, we model the endurance reliability of an advanced data protection methodology like the intra-disk Redundant Array of Independent Disks (RAID) applied on mid-1X Triple Level Cell NAND Flash-based SSD. The performed investigations include a parametric analysis of the Uncorrectable Bit Error Rate. By developing a dedicated discrete-time Markov-chain model of an SSD we evidenced that intra-disk RAID5 and RAID6 allows achieving an inherent reliability level compliant with the qualification target for enterprise SSD. Finally, we provide a global picture of the disk economy when intra-disk RAID is implemented.