Research And Implementation Of The File System On Large-scale Nand Flash Based On Vxworks

NAND Flash Memory is widely used in embedded systems as a data storagedevice for its large capacity, shock resistance property, high function/price ratio, etc.The design and development of NAND Flash file system being an important part of thecurrent embedded software development field. Especially with the rising capacity ofNAND Flash, how to get an efficient and reliable file system for embedded systems byutilizing the changes of its physical properties which is the main research interests ofthis thesis. To meet the needs of storage system based on Large-scale NAND Flashunder VxWorks OS for our project, several aspects of research are carried in this thesisby Using the VxWorks6.6 and MPC8379E embedded system developing platform:1) Thorough analyzing the mechanism of the block device drivers and thecharacteristics of file system in the VxWorks I/O system, analysis the limitations ofFlash file system with TrueFFS drive technology on Large-scale NAND Flash Memory,the thesis given a implementation procedure of Large-scale NAND Flash file systembased on VxWorks embedded system platform.2) Based on knowing the mechanism of NAND Flash operating, studying theMPC8379E hardware architecture and transmission mechanism of FCM interface, thethesis introduced the implement method of the driver for NAND Flash using FCMinterface in VxWorks OS.3) Through the analysis of the NFTL storage management mechanism, given aprocedure of implanted into VxWorks6.6 OS. On the basis of these, introduces theimplementation methods of TrueFFS on flash.4) Aiming at the limitations of flash file system with NAND Flash TransitionLayer (NFTL) on Large-scale Nand Flash Memory, the thesis presented improvedalgorithm and given an implementation procedure in detail for increases the speed ofmount device, read/write operation and enhance reliability by take full advantage of thestructures and properties of Large-scale NAND Flash.5) Thorough understanding of the structure of YAFFS2 file system and YAFFS2Direct interface, achieve the YAFFS2 in VxWorks.Finally, A comparison is made between NFTL and Log-structured file systemYAFFS2 ,data show that both the file system have advantages and disadvantages, it'snecessary to choose in order to get the best efficiency in different applicationenvironments.