TreeFTL: Efficient RAM management for high performance of NAND flash-based storage systems

Abstract

NAND flash memory is widely used for secondary storage today. The flash translation layer (FTL) is the embedded software that is responsible for managing and operating in flash storage system. One important module of the FTL performs RAM management. It is well-known to have a significant impact on flash storage system's performance. This paper proposes an efficient RAM management scheme called TreeFTL. As the name suggests, TreeFTL organizes address translation pages and data pages in RAM in a tree structure, through which it dynamically adapts to workloads by adjusting the partitions for address mapping and data buffering. TreeFTL also employs a lightweight mechanism to implement the least recently used (LRU) algorithm for RAM cache evictions. Experiments show that compared to the two latest schemes for RAM management in flash storage system, TreeFTL can reduce service time by 46.6% and 49.0% on average, respectively, with a 64MB RAM cache.