Building Reliable High-Performance Storage Systems: An Empirical and Analytical Study
Zhi Yong Qiao, Song Fu, Hsing‐Bung Chen, Bradley W. Settlemyer · 2019
Due to the vast storage needs of high performance computing (HPC), the scale and complexity of storage systems in HPC data centers continue growing. Disk failures have become the norm. With the ever-increasing disk capacity, RAID recovery based on disk rebuild becomes more and more expensive, which causes significant performance degradation and even unavailability of storage systems. Declustered redundant array of independent disks shuffle data and parity blocks among all drives in a RAID group, which aims to accelerate RAID reconstruction and improve performance. With the popularity of ZFS file system and software RAID used in production systems, in this paper, we extensively evaluate and analyze declustered RAID with regard to the RAID I/O performance and recovery time on an high performance storage platform at Los Alamos National Laboratory. Our empirical study reveals that the speedup of declustered RAID over traditional RAID is sub-linear to the parallelism of recovery I/O. Furthermore, we formally model and analyze the reliability of declustered RAID using the mean-time-to-data-loss and discover that the improved recovery performance leads to a higher storage reliability compared with the traditional RAID.