New techniques for real-time FAT file system in mobile multimedia devices

Flash memory has become the most important storage media in the mobile multimedia products such as MP3 players, mobile phones, and digital cameras. Most mobile multimedia devices, however, use one of the conventional FAT file systems slightly modified for flash memory environments. Our analysis shows that theses file systems have some restriction in recording a live multimedia stream stably because they have irregular write response times. In this paper, we have considered the problems of the existing FAT file system and propose two new techniques to solve the problems. The first technique called sector reservation method reduces internal overhead effectively. And the other method called ACPA avoids the periodic cluster allocation of the conventional FAT file system and removes the frequent modifications on the file allocation table in the FAT file system. To evaluate our new techniques, we implemented a prototype real-time FAT file system on ARM9 board with our two novel techniques. The experimental results show that our system achieves our goal successfully in that its write response times are very deterministic and more uniform.