一种基于YAFFS2的静态磨损均衡算法设计

针对已有算法大多基于FTL(Flash Translation Layer)闪存存储体系设计，无法直接应用到闪存文件系统的情况，基于YAFFS2闪存文件系统设计了一种静态磨损均衡算法。考虑不同数据冷热属性的差异，设计了两种不同的块分配策略，在减缓最大擦除次数增长速度的同时，加强对冷数据占用块的利用；利用闪存块擦除次数在物理空间上分布的随机性，简化了块分配策略中的搜索过程，降低了算法复杂度；采用不均衡度阈值作为算法触发条件，保证良好的均衡效果。实验结果表明，算法降低了擦除次数方差，提高了闪存磨损均衡度，可有效延长闪存寿命，提高闪存存储系统的可靠性。

Design of Static Wear-leveling Algorithm Based on YAFFS2

Since most of the existing wear-leveling algorithms, designed for FTL-based flash memory storage system, can not be well applied to the flash file system, a static wear-leveling algorithm based on YAFFS2 is designed in this paper. Considering the different data attributes, two different block allocation strategies are proposed to speed down the growth of maximum erasure count and strengthen the utilization of the blocks occupied by the cold data. With the distribution of the block erasure counts in the flash physical space randomized, the algorithm simplifies the search operation in block allocation process, which reduces the algorithm complexity. The uneven threshold trigger mechanism also ensures a outstanding wear-leveling effect.The experiment results show that the algorithm reduces the variance of the erasure counts and improves the degree of evenness, which can prolong the service life of flash and improve the reliability of flash storage system effectively.