The Design Of Reduced Embedded File System

An embedded file system is the software used to operate, organize and manage in embedded systme. It translates the physical operations of memory blocks into the logical operations of files. Although the technology is faultless on the traditional disk file system, it showed fatal bug in flash. Along with the rapid development of microelectronics technology, Flash has a tendency to replace the disk as it shows many advantages, such as high storage density, low-cost, small size, anti-vibration, etc. There are many flash file system products in recent years, flash file system has become a hot research direction. But most of them to the computer system as a platform to support complex file operations. The redundant system functions wasted system resources and reduce the time performance in the single-user embedded electronic products, which need just some basical file operations.The Reduced Embedded File System(REFS) is designed for flash memory in the paper. System resource management uses the "red-black tree" structure to ensure the system's worst-case time performance; REFS is also designed to save space and wear balance; To support long file names; REFS achieved the application program interface for file operations, such as create, copy, delete, move and file reading and writing, user task or program can use these interface functions operate or control of files in an operating system or no operating system.REFS using the block address shift strategy to abandon the mapping between logical address and physical address, and improved file reading and writing performance greatly. REFS manage 2TB of storage space and support 4GB of large files. REFS uses an index table in inode, which link to the data blocks of file, to organize file flexibly. In the file update, putting the modified data in one block, may effectively reduce the production rate of dirty blocks, so that the storage life is extended. REFS recorded the effective bytes number in each of data block in the OOB, therefore, inserting not-filled data blocks can be achieved to edit, modify, delete data on the file, so it is unnecessary to modify all of the data block after the modify point. REFS is provided only for system files edit, modify, delete data operations, not for user's program. Users can complete these operating in the computer system.