Hashing Directory Scheme for NAND Flash File System

Flash memory, especially NAND flash memory, has become a major method for data storage in mobile systems because of its small size, shock resistance, and low power consumption. When the flash memory is used, conventional file systems cannot be used upon a bare flash memory due to physical characteristics. Instead, few flash file systems are developed which use the direct interfaces with flash memory. However, their data recording method have problems as the capacity of flash increases, because these use log based data recording method, which means that they encapsulate the metadata information into the data node for all files when data are written. Their method is good for the small capacity of flash memory, but not adequate for large sizes because it consumes more mount time, memory footprint and operation times as capacity increases. In this paper, we present an efficient metadata management scheme of flash file system for giga scale flash memory. Specifically, we design the hashing directory structure for directory management and two level index structure for file index management. These management scheme can reduce the file system mount time and memory footprint during runtime.