(A) file system based on flash memory

Abstract

Making equipment small and reducing power consumption are two of key requirements in a mobile computing. Flash memory device has been thought as a storage alternatives of disk for mobile computing, since it consumes relatively little power, and has low latency and high throughput for read accesses, and reasonable shock resistance. Nevertheless, flash memory has main drawbacks, include erase-before-write, limited erase/write cycles. Our two main design goals are to overcome the drawbacks of flash memory and to specialize the architecture for mobile computing. To avoid the limitations due to flash memory``s restricted number of cycles and its inability of in-place-update, we studied a file system that has two types of inode those were allocated in separated segments and data being grown sequentially in its segments as a Log-structured File System(LFS) does, and uses a segment manager to manage the log in segments and to distribute the chance for segments to be erased uniformly. And we makes a variation on data allocation mechanism to support execute-in-place feature. Despite the added work to overcome the drawbacks of flash memory in novel design, measurement shows that the throughput in read operation and write operation is about 28.92 Mbytes/sec and about 158.67 Kbytes/sec respectively. We also find that the amount of invalidated memory in flash memory being reduced about 14.75 % in novel design against in a conventional design.