Research And Implementation On Solid State Storage Technology Based On NAND Flash Memory

With the continuous development of electronic integrated circuit technology, the performance of Microprocessor is continuously improving, and the performance of storage system is becoming a bottleneck of computer systems. The traditional disk can't meet the demand because of it's huge delay. Flash memory is becoming more popular due to it's fast read and write speed and it's non-volatile characteristics.The main research topic is NAND flash memory based storage systems, and the performance optimization technology in it. First we designed a paralleling storage system based on NAND flash memory. The main features of the storage system are: using the parallel and pipelining techniques to improve it's performance, and using PCI Express 2.0 high-speed interface to connect it to the host device, and using large capacity volatile DRAM as it's write buffer. To use DDR as the cache of flash memory, this project designed a DDR controller.Second, because of NAND flash memory's characteristics of erased before write which make the write performance of NAND flash memory is very low, we presents a log-based flash translation layer using offset priority strategy in the paralleling storage system based on NAND flash memory, committing reducing the flash memory's erase operation. The test results show that the offset priority strategy not only can reduce the flash memory's erase operation, but also can reduce the overall execution time and average delay of garbage collection, which increases the service life of flash memory and improves the performance of flash memory.Finally, adding cache to the flash memory is an effective solution to improve it's performance. This research adopted a block-level priority LRU policy to be used with our offset priority strategy, which can improve the performance of flash memory more effectively.