Abstract:

Unlike a hard disk, there is no mechanical parts in flash. Therefore, the reason of disk fragmentation weakening the performance of the flash is not seekdelay, but is its own characteristics. Through inducting the Flash Translation Layer(FTL), the existing file system can directly be applied to the flash. At the same time, FTL is the reason of performance degradation of flash under  fragmentations. When there is some fragmentations in flash, the difference of merge operation types result in the performance degradation. On the basicis of  reason analysis,a scheme of padding the spacing is put forward and its validity is demonstrated.

Key words: NAND flash;flash translation layer;disk fragmentation;merge