Research On Manage Algorithm Of Solid State Disk With PCI Express Interface

Solid state disk, which is one of the solutions to the problem of data storage, has a lot ofadvantages such as high quake resistance, wide temperature range, reliable and the energyconservation. Hard disk drive is being replaced by solid state disk which is widely used to labtop,tablet personal computer and other digital products. Nowadays, the speed of solid state disk withSATA interface has reached the limitation. As the development of information technology, theamount of data becomes larger and larger. If using the solid state disk with SATA interface tostore the information, the speed can’t meet people’s requirement. So improving the solid statedisk’s reading and writing speed is very necessary. Most solid state disk’s storage medium isNAND flash and its erase data unit is based on block but the reading and writing data unit isbased on page. The NAND flash should be erased before be written and the erase time is limited.So if the erase time is not balance, the solid state disk’s lifetime will be affected. At present, thealgorithm to solve this problem on the market is not perfect.So in order to improve the solid state disk’s speed and extend its lifetime, this paper givessome methods as following:(1) Use PCI Express interface to replace SATA interface to improve the reading and writingspeed. PCI Express has a high speed and the bandwidth can be extended easily, so it isthe trend in the future. This paper implements the Linux driver of the PCI Expressdevice. (2) Use the multi-channel technology to operate the solid state disk parallelly. This methodcan read or write the NAND flash at the same time. So it can save the time running inthe internal of the flash and improve the speed of the solid state disk.(3) Use the address mapping algorithm which is based on the page. This method can storethe mapping addresses which are used frequently in the DDR and others in the NANDflash. The mapping based on the page is very flexible to get the physical address by thelogic address. So the solid state disk’s speed can be improved.(4) The garbage collection algorithm and the wear leveling algorithm which are based on themulti-channel are implemented via the binary tree to find out the dirtiest blocks and thenerase these blocks parallelly. This method makes all the blocks’ erase time be balancedand extends the solid state disk’s lifetime.This paper firstly describes the research’s background, significance, status at home andabroad. Secondly it introduces the basic knowledge which is related with the technology neededto implement, including the storage medium NAND flash and the PCI Express2.0interface.Thirdly it introduces the implementation of Linux device driver of solid state disk and the keyalgorithm of the flash transaction layer, such as the multi-channel technology, address mappingalgorithm, garbage collection algorithm and the wear leveling algorithm. Finally, it introduces thetest method, test tools and test process, and then gives the test result. From the result, it provesthat the design of solid state disk’s algorithm in this paper is more efficient comparing withtraditional SATA interface. The way of reading and writing parallelly accelerates the speed andthe wear leveling algorithm prolongs the solid state disk’s working life.