TrueFFS文件系统的改进

发布时间：2019-05-29 05:19

【摘要】：TD-SCDMA和TD-LTE是当今世界通信的两大主流业务,基站的可靠稳定运行是保障这两大业务的根本。在基站的主控板卡上,用Flash芯片存储着可执行程序,对Flash的操作是基于TrueFFS这套文件系统的。在任务运行期间,一些打印信息和告警信息都写入Flash芯片中。但是在系统运行期间,会出现日志乱码、自动格式化等问题。针对上面出现的问题,本人所做工作有以下几方面： (1)学习并分析TrueFFS这套文件系统的源码,找出了该套文件系统比较核心的翻译层。对翻译层中比较重要的块分配、虚拟映射、页表进行重点分析。其中块分配存放的是每个逻辑扇区的状态和对应的虚拟地址,虚拟映射存放的是虚拟扇区号和逻辑扇区号的对应关系。 (2)定位外场反馈回来的问题,提出改进该套文件系统的方案。对于flash自动格式化,这种现象发生在底层unit的头部被改写之后。这种现象的发生说明对unit头部的保护不够,增加对unit头部的保护。文件系统出现读写错误,这说明在寻址的时候出现了问题。而和寻址有关系的是文件系统的块分配和虚拟映射,增加对这些关键数据的备份,并在数据读写时兼用主备份,以提高系统的可靠性。文件出现乱码,这种情况是由位翻转引起的。添加ECC校验,使得系统具有自动纠错的功能。经过改进后的该套文件系统在测试中比较稳定,没有文件乱码和自动格式化的情况发生。在此期间也出现电平跳变的现象,但改进后的文件系统对该种问题进行了报错与修复。
[Abstract]:TD-SCDMA and TD-LTE are the two mainstream services of communication in the world today, and the reliable and stable operation of base station is the foundation of ensuring these two services. On the main control card of the base station, the executable program is stored with Flash chip, and the operation of Flash is based on the file system of TrueFFS. During the operation of the task, some print information and alarm information are written into the Flash chip. However, during the operation of the system, there will be problems such as log scrambling, automatic formatting and so on. In view of the above problems, my work has the following aspects: (1) learn and analyze the source code of TrueFFS file system, find out the core translation layer of the file system. The important block allocation, virtual mapping and page table in translation layer are analyzed. Among them, the block allocation stores the state and the corresponding virtual address of each logical sector, and the virtual mapping stores the corresponding relationship between the virtual sector code and the logical sector code. (2) the problem of field feedback is located, and the scheme of improving the file system is put forward. For flash automatic formatting, this occurs after the header of the underlying unit is rewritten. The occurrence of this phenomenon shows that the protection of unit head is not enough and the protection of unit head is increased. A read and write error occurred on the file system, indicating that there was a problem with addressing. It is related to addressing that the block allocation and virtual mapping of the file system increase the backup of these key data and use the main backup when reading and writing the data in order to improve the reliability of the system. There is a random code in the file, which is caused by bit flipping. Add ECC check, make the system have the function of automatic error correction. The improved file system is stable in the test, and no file scrambling and automatic formatting occurs. During this period, there is also the phenomenon of level jump, but the improved file system reports and repairs this kind of problem.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TP333;TP368.1

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