Design and Implementation of Hybrid Shingled Recording RAID System
Zhengwu Lu, Gang Zhou · 2016
Shingled write disks (SWDs) adopt shingled magnetic recording (SMR) to overcome the density limit faced in the conventional hard disk drives (HDDs) and RAID5 provide high performance and high reliability for reasonable cost. Meanwhile Flash memory based Solid State Drives (SSDs) are becoming an important part of computer storage hierarchy to significantly improve performance and energy efficiency. In this work, we present a novel shingled recording RAID, which turned the traditional disks in RAID into SWDs with considerable performance. We implemented the storage system in 3 models: first, we take the SSD as the cache of RAID on the top of storage system, second, we regarded SSDs as caches of every single SWD, in the third way, we have SSDs as caches for both RAID and every single SWD. We designed a backup strategy for model 1 and a hot data select algorithm for cache. We have implemented SWDs RAID on Linux system. Extensive experiments have been carried out to evaluate the three model of SWDs RAID. Experimental results show that shingled recording RAID could maintain the performance of traditional RAID even with 1.83% performance improvement by model 1. While the backup policy improve the reliability of SWDs RAID in return for 2.03% IOPS decrease.