Dysource: a high performance and scalable NAND flash controller architecture based on source synchronous interface

Flash controllers play critical roles in determining the performance of flash storage. But current controller architectures based on asynchronous interface cannot meet the ever-increasing demands of performance for new large-scale flash storage systems, due to their limitations of I/O bandwidth and scalability. In this paper, we propose an advanced NAND flash controller architecture, called Dysource, to improve performance and scalability of flash storage. Based on the high-speed source synchronous interface supported by ONFI standard, we propose a dynamic scheduling strategy to extend exploration of parallelism to target level. Moreover, we design a novel instruction "MOVE" and incorporate it into existing instruction set to speed up garbage collection for higher performance. The experimental results suggest that the performance of the Dysource controller is 4.6 to 9.4 times better than the traditional asynchronous controller as for organization of 8 channels x 8 targets. Moreover, by employing architecture of multiple Dysources, the storage system can scale to arbitrary number of channels and 32 targets at most per channel with high growth rate of performance.