基于工作负载感知的固态硬盘阵列系统的架构设计与研究

Research of SSD Array Architecture Based on Workload Awareness

在RAID-0阵列中设计了一种基于冷热数据分离存储的固态硬盘阵列系统架构HA-RAID,并结合滑动窗口技术进行优化.其主要思想是,利用固定长度的滑动窗口将阵列系统中的盘划分为普通盘和热点盘,热点盘专门存放热数据,普通盘存放普通数据,且阵列中各盘的角色随着滑动窗口的移动而不断变化.在8块商用固态硬盘组成的RAID-0阵列系统上对HA-RAID予以实验分析.实验结果表明,相比于未引入冷热数据分离机制的原始RAID-0做法,HA-RAID可以将热数据相对均匀地存储到各个盘上,很好地实现了阵列系统级的负载和磨损均衡,从而将阵列中热点盘出现的比例降低到几乎为0.在真实的企业级工作负载下,相比原始RAID-0,HA-RAID减少12.01%～41.06%的平均响应时间,很好地实现了阵列系统级的I/O性能提升.

The fixed data layout of traditional array system and the locality of workloads cause the partial disks of the array system to become hot disks,which affects the reliability and the overall concurrency performance of the array system.This paper proposes a new RAID architecture for SSD array systems,HA-RAID,which leverages hot cold data separation and sliding window techniques.The main idea is that HA-RAID divides the disk array into hot disks and ordinary disks,which stores hot data on hot disks and cold data on ordinary disks,and it changes the role of each disk dynamically by moving a fixed-length sliding window.So,each disk has the opportunity to become a hot disk and stores hot data which achieves the purpose of storing hot data evenly on each disk.Experiments under real-world workloads on a RAID-0 array system composed of eight commercial SSDs show that HA-RAID can achieve an even distribution of hot data across all disks and reduce the percentage of hot disks appearing in the array to almost zero.This implies that HA-RAID achieves load balance and wear balance at the device level.In terms of performance,HA-RAID reduces the average response time by 12.01%~41.06% which achieves the I/O performance enhancement,compared with traditional RAID-0 array.