Research And Implementation Of The Parallel Storage System Based On NAND FLASH

With the development of the information technology, it is common for users to have more data storage capacity and speed requirements, the requirements of large capacity and high reliability storage system bring challenges to the storage research fields. But the mechanical disk devices which are used by traditional computer storage system have become bottlenecks of storage system performance because of memory capacity and I/ O access latency. At the same time, with the progressive development and a series of technological changes, Flash memory as non-volatile storage medium which has rapid read and write speed and non-volatile characteristics and great storage capacity and no mechanical mechanism and good potential for parallelism and low cost gradually revealings its great advantage, and attracts the attention of the domestic and foreign scholars and the industry, it may be an trend to replace traditional disk in the future.This paper designs and implements a parallel storage systems based on NAND FLASH, using FPGA as the experimental platform and SANSUNM's NAND FLASH chips as storage unit, this storage system can well meet the system speed and reliability and security needs and have good parallelism. The main work and innovation of this paper include:Firstly, we carried out a detailed research on related technologies and research status quo of NAND FLASH storage, and analyzed the advantages of building storage systems and the problems that would be encountered. Through the study of the internal structure and interfaces of NAND FLASH chip, we proposed the feasibility and the target to build a mass parallel storage system.Secondly, according to the structural characteristics of the FLASH chip we designed parallel storage card based on NAND FLASH. With this card as base hardware, we completed the module design of storage system, including: main logic module design, ECC module design, cross switch module design, random-order module design.Thirdly, we implemented the parallel storage system based on NAND FLASH and completed the simulation of data read, write, delete and other operations, ensured the system's normal data access operation on FPGA. The storage system achieved 600M + access rate by FPGA test on 4*8G test platform.Fourthly, against the bad block problem which is brought by the introduction of parallel technology on solid-state flash memory system, we presented an efficient bad block management strategy of NAND FLASH multiple parallel solid storage systems, which can save bad block storage space and reduce the bad block processing cost by using parallel storage bad block coding technology, solve the same location bad block problem effectively by using bad block reconstruct technology. We put forward out of order Flash memory execution model after the research of execution model of Flash chip command order,and we designed the NAND FLASH storage controller based on out of order execution model.