GC-Steering: GC-Aware Request Steering and Parallel Reconstruction Optimizations for SSD-Based RAIDs
GC-Steering: GC-Aware Request Steering and Parallel Reconstruction Optimizations for SSD-Based RAIDs
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DOI：
10.1109/tcad.2020.2974346
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发表时间：
2020-12
影响因子：
2.9
通讯作者：
Suzhen Wu;Weidong Zhu;Ying Han;Hong Jiang;Bo Mao;Zhijie Huang-;Liang Chen
中科院分区：
文献类型：
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作者：
Suzhen Wu;Weidong Zhu;Ying Han;Hong Jiang;Bo Mao;Zhijie Huang-;Liang Chen
基于固态硬盘(SSD)的独立磁盘冗余阵列(RAIDs)被广泛部署在高端企业系统中，为数据密集型计算提供高性能和高可靠的存储。然而，每当用户I/O请求与正在进行的垃圾收集(GC)操作发生冲突时，基于SSD的RAID的性能就会显著下降，这会导致尾部延迟。此外，固态硬盘的性能特性使得传统的基于硬盘的磁盘阵列重建算法不兼容或不适合基于固态硬盘的磁盘阵列。在本文中，我们提出了感知GC的请求引导(GC-Steering)，这是一种感知基于SSD的磁盘阵列中的GC进程的方案，以显著提高基于SSD的磁盘阵列的性能和可靠性。GC-Steering有效地将当前处于GC状态的流行读请求和所有寻址到SSD的写请求外包到临时空间，例如专用备用SSD或RAID中每个SSD的保留空间。GC-Steering还通过请求转向和并行恢复来加速故障恢复过程的性能。我们对由类HPC和真实企业级工作负载驱动的轻量级GC转向原型进行的广泛评估表明，与最先进的本地GC和全局GC方案相比，GC转向方案显著降低了平均响应时间63.3%和65.8%。此外，与正常状态相比，GC-Steering方案还显著降低了RAID重建过程中的平均响应时间62.3%。
Solid-state disk (SSD)-based redundant array of independent disks (RAIDs) have been widely deployed in high-end enterprize systems to provide high-performance and highly reliable storage for data-intensive computing. However, SSD-based RAIDs suffer from significant performance degradation whenever user I/O requests conflict with the ongoing garbage collection (GC) operations which introduce tail latency. Moreover, the performance characteristics of SSDs make the traditional HDD-based RAID reconstruction algorithms are not compatible with or suitable for SSD-based RAIDs. In this article, we proposed GC-aware request steering (GC-Steering), a scheme aware of the GC process within an SSD-based RAID, to significantly boost the performance and reliability of SSD-based RAIDs. GC-Steering effectively outsources the popular read requests and all write requests addressed to the SSD currently in the GC state to a staging space, such as a dedicated spare SSD or the reserved space of each SSD within the RAID. GC-Steering also accelerates the performance of the failure-recovery process by both request steering and parallel recovery. Our extensive evaluations on a lightweight GC-Steering prototype driven by HPC-like and real-world enterprize workloads show that the GC-Steering scheme significantly reduces the average response time by an average of 63.3% and 65.8%, compared with the state-of-the-art local GC and global GC schemes. Moreover, the GC-Steering scheme also significantly reduces the average response times by an average of 62.3% during RAID reconstruction than the normal state.