Study On High-speed Flash Translation Layer For Solid State Disk

In recent years, NAND flash has been widely used in laptops, Ultrabook, PCs andServers. However, the technologies of scaling down and multi-level-cell make theproperty of flash storage devices keep decreasing. The endurance of NAND flash cell,the access time of NAND flash and the reliability of NAND flash are all becomingworse. On the other hand, the consumers and industrial applications need the NANDflash become faster, cheaper, durable and more reliable. This made the technology ofNAND flash management much more important. The Flash Translation Layer containsalmost all the technologies of NAND flash management and need to be trade-off amongthe performance of system lifetime, speed, reliability and resource overhead. What’smore, the design of Flash Translation Layer should consider the performancedegeneration after long-term use and the support of various applications.This paper presents the design and implementation of a Flash Translation Layerincluding the wear-leveling, bad block management, garbage collection and addressmapping. Two new wear-leveling algorithms are proposed, which are called ChangingThredhold Triple Pool algorithm and Block Status Table algorithm. In this paper, asoftware testing platform and a hardware testing platform are constructed. The softwaretesting platform is used to evaluate the function of Flash Translation Layer and thehardware testing platform is used to test the response time of Flash Translation Layer.The result of evaluation shows that the proposed Changing Thredhold Triple Poolalgorithm can obviously impove the maximum writeable data in6different tracescompared with4other wear leveling algorithm. And the Block Status Table algorithmcan also impove the maximum writeable data and reduce the comsume of SRAM. Thehardware testing shows that the Flash Translation Layers has a low response time whichcan support the high-speed applcations.