MNFS : A multimedia non-linear editing file system for PRAM-NAND flash memory

Abstract

In the past, two main storage technologies, a hard disk drive(HDD) and flash memory chips, had its own distinct uses. The hard disk drive technology was used in machines requiring much storage spaces, such as servers, PCs, laptops while flash memory was used in devices that needed less storage capacity, such as digital cameras, cell phones, and embedded controllers. But recent users’ desires converge on both areas; small platform but large storage capacity. Accordingly, considering the capacity, HDD was thought of as the solution for such devices but HDDs are not fit to small hand-held devices for many reasons. In contrast, NAND has been thought as the main storage replacing HDDs according to the recent advanced technology. Moreover, with the increasing storage capacity, the main features of NAND, for example, light weight, shock-resistance, no seek time are very attractive to the manufacturers and developers. Considering many advantages of NAND, it will take the many places of HDDs. YAFFS is a de facto standard flash memory file system for NAND flash-memory but it has problems to be an alternative for multimedia file system;it do not have non-linear editing support and it may takes too much time to mount if the NAND is not clean. Moreover, it consumes pages for meta-data which cause the performance degradation by frequent updates and garbage collection. Another advanced flash file system, PFFS was developed to solve the problems of YAFFS. However, PFFS also is not suitable to be used as a multimedia file system with following reasons. First, PFFS is based on the disk-based EXT2 file system, which means it spends too much storage for metadata because the PFFS uses pointers for data pagess. Second, because PFFS only uses 13 direct, 2 indirect, 2 doubly indirect entries, the largest file size that PFFS can point is 1GB which is not enough size for multimedia file system. Third, PFFS do not consider the non-linear editing desire. Lastly, it also spends NAND...