Improvement Of True Flash File System

TD-SCDMA and TD-LTE are two main businesses in communication industry. Reliable and stable run of the base station is the key of protecting them. As the main control board of base station, it uses flash chip to store executable programs. At the same time, it uses true flash file system to control flash.During the task running some print information and alarm information are written to the flash chip. But, log garbled, automatic formatting and other issues would happen.To solve problems above, I have done work as follows:(1) I study the source code of true flash file system, finding translation layer is the key. It includes some important factors:block allocation map, virtual map and pagetable. BAM stores the state of each logical sector and the corresponding virtual address. Virtual map stores correspondence between the virtual sector number and the logical sector number.(2) I analysis the problems and propose suggestions to improve this system. After unit header changed, flash automatically formats, which illustrates that protection of unit header is not enough.So, I add protection of unit header. Read and writes errors indicates that there are problems when addressing. It has relationship with block allocation map, virtual map. They need to be backed up to improve system reliability. Flie garbled is caused by bit flip. Adding ECC can help system to correct errors automatically.After improving the file system, base stations run stablely during these mounths. Log garbled and automatic formatting has never happened again. Level jump phenomenon also appeared during this period, but it was solved by the improved file system.