DLOOP: A Flash Translation Layer Exploiting Plane-Level Parallelism

Abstract

A flash translation layer (FTL) is a software layer running in the flash controller of a NAND flash memory solid-state disk (hereafter, flash SSD). It translates logical addresses received from a file system to physical addresses in flash SSD so that the linear flash memory appears to the system like a block storage device. Since the effectiveness of an FTL significantly impacts the performance and durability of a flash SSD, FTL design has attracted significant attention from both industry and academy in recent years. In this research, we propose a new FTL called DLOOP (Data Log On One Plane), which fully exploits plane-level parallelism supported by modern flash SSDs. The basic idea of DLOOP is to allocate logs (updates) onto the same plane where their associated original data resides so that valid page copying operations triggered by garbage collection can be carried out by intraplane copy-back operations without occupying the external I/O bus. Further, we largely extend a validated simulation environment DiskSim3.0/FlashSim to implement DLOOP. Finally, we conduct comprehensive experiments to evaluate DLOOP using realistic enterprise-scale workloads. Experimental results show that DLOOP consistently outperforms a classical hybrid FTL named FAST and a morden page-mapping FTL called DFTL.