Improving flash wear-leveling by proactively moving static data

Motivated by the strong demand for flash memory with enhanced reliability, this work attempts to achieve improved flash-memory endurance without substantially increasing overhead and without excessively modifying popular implementation designs such as the Flash Translation Layer protocol (FTL), NAND Flash Translation Layer protocol (NFTL), and Block-Level flash translation layer protocol (BL). A wear-leveling mechanism for moving data that are not updated is proposed to distribute wear-leveling actions over the entire physical address space, so that static or rarely updated data can be proactively moved and memory-space requirements can be minimized. The properties of the mechanism are then explored with various implementation considerations. A series of experiments based on a realistic trace demonstrates the significantly improved endurance of FTL, NFTL, and BL with limited system overhead.