SREA: A self-recovery effect aware wear-leveling strategy for the reliability extension of NAND flash memory

Abstract

With aggressive scaling and multilevel cell technology, the reliability and lifetime of the NAND flash degrades. To address this issue, a Self-Recovery Effect Aware (SREA) strategy is proposed to extend the storage reliability of the NAND flash. The key purpose of SREA is a wear-leveling strategy based on the self-recovery effect of the NAND flash. First, this study verifies the self-recovery effect of the NAND flash based on our hardware-software codesigned experimental platform; then, we propose the concept of relaxation time (tr). The change rule of the data retention error under different degrees of tr for blocks subjected to different program/erase (P/E) cycles is also investigated. The experimental results show that there is an approximately 60% gap of retention error rate when tr = 0 h and tr = 6 h after the same retention time. In addition, we apply the experimental rules to the wear-leveling strategy. Compared with the traditional wear-leveling strategy that does not consider tr, the maximum data reliable retention time of SREA can be extended by 2.67×.