Research On 3D NAND Flash SSD Firmware Based On NVME Interface

With high density,large capacity,non-volatile features,NAND Flash is widely used in the storage area.The NVMe interface has features such as high bandwidth,fast read/write speed,and supports for multiple queues.It requires hardware,firmware,and software layers to cooperate with each other to improve parallelism and performance of the NAND Flash.The three-dimensional stacking technology has further increased the storage density and storage capacity of NAND Flash,but it has brought about more serious adjacent page programming interference.The existing work proposes an interleaving programming algorithm at the MTD driver layer to reduce the programming influence on the data,but the space utilization is low,and the algorithm is not effective when the free space is low.Aiming at the serious of 3D NAND Flash adjacent page programming interference,a sequential and interlace hybrid FTL algorithm is designed at the device firmware layer.It proposes the detailed split of physical blocks and interference detection strategies to improve space utilization and further reduce program interference;proposes multi-queue processing strategy,assigns different heat data to appropriate queue programming,and uses cold data in sequential programming mode to enhance space utilization;proposes a strategy for prioritizing high page data migration to optimize high page programming efficiency.The design implements NVMe firmware so that the device supports the NVMe interface.Different loads are tested on the SSD simulator.The results show that the SIH-FTL algorithm can reduce the read disturbance error by 10% and the write disturbance error by 25% on average compared with the existing algorithms.Through partial testing of hot and cold data processing and soft threshold early recovery strategies,it was found that adding hot and cold data processing has a significant effect on improving write reliability,reducing write interference by approximately 30%;soft threshold early recovery strategy has a significant effect on improving read reliability.Decrease reading interference by 17%.By testing on a laboratory-developed SSD hardware platform,the NVMe firmware program can communicate with the general NVMe driver and make the device work properly.