关键词: 闪存, 固态盘, 垃圾回收, 磨损均衡, 使用寿命

Abstract: Due to NAND Flash’ inherent restrictions like erase-before-write and a larger erase unit, flash-based solid-state drives (SSDs) demand garbage collection operations to reclaim invalid physical pages. However, the high overhead caused by garbage collection would significantly decrease the performance and lifetime of SSDs. Existing garbage collection (GC) algorithms only focus on some steps of the garbage collection operation, and none of them provides a comprehensive solution that takes into consideration all the steps of the GC process. On the basis of detailed analysis of the GC process, our paper present WPO-GC, a whole process optimized garbage collection algorithm, which integrates optimizations on each step of the GC in order to reduce the negative impact on normal read/write requests and SSDs’ lifetime in maximum extent. Moreover, we implement the WPO-GC on SSDsim which is an open source SSD simulator to evaluate its efficiency. The experimental results show that the proposed algorithm can decreases read I/O response time by 20%-40% and write I/O response time by 17%-40% respectively, and balance wear nearly 30% to extend the lifetime, compared with the related work.

Key words: flash memory, solid state disk, garbage collection, wear-leveling, lifetime