SCFTL: An efficient caching strategy for page-level flash translation layer

The increasing capacity of NAND flash memory results in larger page size. Since a larger page requires longer access time, the performance of a flash translation layer (FTL) that stores its mapping table in flash pages is degraded. An economical FTL named SCFTL is proposed to avoid such issues caused by the larger page size. In order to reduce spatial requirements, SCFTL employs a demand-based caching mechanism for the page-mapping table. Unlike other FTLs, SCFTL facilitates two techniques for delicately exploiting the spatial locality. In addition, the replacement algorithm is customized for the asymmetrical access time of flash memory. The experiments show that the average overhead of SCFTL in terms of access time is only 6.89%; this overhead is 75.96% and 11.35% lower than the state-of-the-art FTLs. The average cache hit ratio of SCFTL is as high as 0.92 despite the compact memory footprint. Because of the outstanding cache utilization, SCFTL still achieves high performance even though the page size is larger.