LINUX交换系统不支持在闪存(NAND flash)上直接建立交换区域。虽然可以使用NFTL/FTL层或者FASS闪存交换系统实现在闪存上建立交换分区。然而,这两种方法都采用静态分配交换区域,将交换系统的读写磨损限制在了闪存固定的某个区域,可能会造成闪存局部过度磨损。提出的SA-YAFFS系统,将交换系统的支持性和闪存文件系统有机统一,在闪存上动态分配交换区域,避免了将交换系统的读写磨损限制在闪存固定的区域,并利用文件系统中大量的空闲空间分担交换系统带来的磨损,避免了局部过度磨损。实验表明,当“文件系统逻辑配额的剩余空闲空间+交换系统逻辑配额”增加到n倍,交换系统导致的磨损为原来的1/n。
The Linux swap system doesn't support the swap area directly on the NAND Flash. Although both NFTL/FFL layer and FASS NAND Flash swap system can realize swap area on NAND Flash,however,both of them allocate swap area statically and limit the I/O of swap system within a certain NAND Flash physical area, which may overwear some part of the NAND Flash. This paper will propose a new system called SA-YAFFS. It integrates the support of the swaps system and the/lash filesystem as an organic unity, and dynamically allocates the swap area on NAND Flash. It avoids limiting the I/O operations of a swap system in a fixed area on NAND Flash. Thus, we can make full use of all the free space of filesystem to level the wear incurred by the swap system so the local over-wear is avoided. Our experiment indicates that we can reduce the wear to 1/n to previous ,when "the remaining free space of the filesystem logical quota + swap system logical quota" rises to n times.