全程优化的固态硬盘垃圾回收方法

发布时间：2018-05-05 22:53

本文选题：闪存 + 固态盘　；参考：《计算机应用》2017年05期

【摘要】：由于NAND闪存的固有限制,写前擦除和擦除粒度较大,基于NAND Flash的固态硬盘(SSD)需要执行垃圾回收以重用失效页。然而垃圾回收带来的高开销会显著降低SSD的性能,也会直接影响SSD的寿命。特别是对于频繁使用的有数据碎片的SSD,垃圾回收带来的性能下降问题将更为严重,现有的垃圾回收(GC)算法各自侧重垃圾回收操作的某个步骤,并没有给出全面考虑各步骤对整体影响的综合方案。针对该问题,在详细剖析垃圾回收过程的基础上,提出了一种全程优化的垃圾回收方法 WPO-GC,在数据初始放置、垃圾回收目标块的选择、有效数据的迁移、触发回收的时间点以及中断处理方式上,尽可能全面地考虑各步骤对SSD正常读写请求和寿命的影响。通过开源模拟器SSDsim上的WPO-GC的有效性验证表明,同典型GC算法相比,WPO-GC可以减少SSD读请求延迟20%~40%和写请求延迟17%~40%,均衡磨损近30%。
[Abstract]:Due to the inherent limitation of NAND flash memory, the granularity of pre-write erasure and erasure is large, so the solid-state disk based on NAND Flash needs to perform garbage collection to reuse invalid pages. However, the high cost of garbage collection can significantly reduce the performance of SSD and directly affect the lifetime of SSD. In particular, for frequently used SSDs with data fragments, the performance degradation caused by garbage collection will be even more serious. Existing garbage collection GCs each focus on one step of a garbage collection operation. There is no comprehensive plan that takes into account the overall impact of each step. In order to solve this problem, on the basis of analyzing the process of garbage collection in detail, a WPO-GC-based garbage collection method is proposed, which can be used in the initial data placement, the selection of garbage collection target blocks, and the migration of effective data. In terms of the time point of triggering the recovery and the way of interrupt processing, the influence of each step on the normal read / write request and lifetime of SSD is considered as comprehensively as possible. The validity of WPO-GC on the open source simulator SSDsim shows that compared with the typical GC algorithm, WPO-GC can reduce the delay of SSD reading request by 20% and write request delay by 17%, and the equalization wear is nearly 30%.
【作者单位】：武汉光电国家实验室(华中科技大学);信息存储系统教育部重点实验室(华中科技大学);
【基金】：国家863计划项目(2015AA016701,2015AA015301) 国家自然科学基金资助项目(61303046,61402189,61472153)~~
【分类号】：TP333.35

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