大容量NAND Flash文件系统中的地址映射算法研究

Space Efficient Mapping Management for Large-scale NAND Flash File System

随着Flash芯片容量的日益增长,如何设计低空间复杂度的Flash管理算法已经成为RAM空间受限的嵌入式存储系统的一个关键问题.本文根据文件在Flash介质上连续存放的特性,引入区段的概念,提出基于极大映射区段的地址映射算法,并使用简单的数据结构和高效的算法来维护映射中的区段,大大减小了Flash文件系统的RAM用量.最后,通过不同应用负载的实验验证了该算法的有效性.在部分应用负载下,可降低高达95%的RAM使用量.

Rash memory is prevalent in embedded storage systems nowadays, but the RAM requirements for address mapping increases as the flash chip＇s volume increases. To design a space efficient management is a critical issue for the resource-limited embedded environment. In this paper a maximum segment based address mapping policy is introduced, according to the sequential programming characteristic of Flash, and the stress of RAM usage can be relieved while keeping the I/O efficiency. A simple but efficient algorithm is proposed which is evaluated under various workloads. Experiments show that the RAM reduction could reach 95%.