읽기전용 및 임시파일의 캐싱을 통한 플래시 파일 시스템의 성능 향상 기법

Abstract

비휘발성 메모리의 하나인 플래시 메모리는 저전력 및 저비용 등의 장점으로 인해 임베디드 시스템에 필수적인 요소로 사용되고 있다. 이러한 장점에 반해, DRAM과 같은 휘발성 반도체 메모리와 비교하여 데이터 쓰기는 느리고, 데이터 업데이트를 위한 블록 소거 (erase) 동작의 오버헤드라는 단점이 있다. 특히 블록 소거 동작은 횟수가 제한되어 있으며, 이는 플래시 메모리의 수명을 결정하는데 중요한 요소이다. 본 논문에서는 플래시 메모리 기반 파일시스템에서 DRAM과 같은 동적 메모리를 사용하여 블록 소거의 횟수를 줄이고 입출력 속도를 향상시키는 기법을 제안한다.; A flash memory which is one of nonvolatile memory is the essential factor of embedded system because of the advantage of low-power and low-cost. Recently portable information technology machinery like mobile phone, PDA, MP3 player and PDA player is getting popular and those machineriesmostly use NAND flash memory as data storage. Compared with volatile memory such as DRAM, NAND memory has disadvantages that data write is slow and block erase for data update has overhead. Especially, the number of block erase is limited and it is important factor to determine lifetime of the flash memory. The flash memory is classified NOR and NAND based on internal structure. NOR stores address as a byte so, can be possible for executing code and random access but, a unitcost is expensive and degree of integration is low. In the other hand, because NAND stores address as a page, it cannot execute code and random access but, a unit cost is low and degree of integration is high. Recently, the study of NAND which has advantages for data storage is actively proceeded to improve performance. In industry, using NAND to implement FAT file system is the kind of standard. In this paper, we propose the methodology that using dynamic memory like DRAM reduce the number of block eraseand improve the speed of input and output in flash memory based file system. When data is read and written using FAT file system in flash memory, we use dynamic memory which input and output is fast to store used data to reduce the number of input and output to memory. Those input and output process is included not in FTL level but in FAT file system level and is selected by developer's intention using file system API.