LazyFTL

Abstract

Flash is a type of electronically erasable programmable read-only memory (EEPROM), which has many advantages over traditional magnetic disks, such as lower access latency, lower power consumption, lack of noise, and shock resistance. However, due to its special characteristics, flash memory cannot be deployed directly in the place of traditional magnetic disks. The Flash Translation Layer (FTL) is a software layer built on raw flash memory that carries out garbage collection and wear leveling strategies and hides the special characteristics of flash memory from upper file systems by emulating a normal block device like magnetic disks. Most existing FTL schemes are optimized for some specific access patterns or bring about significant overhead of merge operations under certain circumstances. In this paper, we propose a novel FTL scheme named LazyFTL that exhibits low response latency and high scalability, and at the same time, eliminates the overhead of merge operations completely. Experimental results show that LazyFTL outperforms all the typical existing FTL schemes and is very close to the theoretically optimal solution. We also provide a basic design that assists LazyFTL to recover from system failures.