A Progressive Garbage Collection Scheme Based on Hotness of Valid Pages for NAND Flash Memory

With the popularity of NAND flash memory, exploiting garbage collection techniques to improve the lifetime of NAND flash memory has become a critical issue in the design of flash translation layer (FTL). However, the existing garbage collection theories always focus on the selection of victim block, but the negative impact on the degree of wear-leveling and the garbage collection overhead is ignored. This paper proposes a progressive garbage collection (PGC) scheme based on the hotness of valid pages. PGC scheme improves the method of choosing the victim block to balance the garbage collection overhead and the degree of wear-leveling and the hotness of valid pages is defined in a new way. Experimental results show that the proposed scheme is better than the existing garbage collection schemes in terms of the number of copy operation, the erase number and the degree of wear-leveling.