A Wear-leveling by Exploiting Block State Change for Log-based Flash Translation Layer

Abstract

Recently, a flash SSD has been widely used as a storage device because of its fast access speed, light weight, and etc. However, since flash SSDs consist of NAND flash memories, the flash SSD cannot perform an in-place update and it has the limited block erasure cycle. Most of flash SSDs employ FTL that offers NAND flash memory as a block device to disk-based systems by hiding these drawbacks. The wear-leveling algorithm is to improve the endurance of NAND flash memory. Several wear-leveling algorithms have been proposed but these algorithms suffer from the performance degradation due to unnecessary flash operations. In this paper, we propose a wear-leveling exploiting block state change for log-based flash translation layer in order to solve the problems. The our proposed algorithm moves the data in order to minimize extra operations and it updates only selected blocks for eliminating unnecessary erase operations. Newly updated cold blocks will be used as next log blocks in order to uniformly erase blocks. Finally, we show that our proposed algorithm yield a better performance on NAND flash memory by comparing it with other wear-leveling algorithms through various experiments.