Caching-aware Garbage Collection to Improve Performance and Lifetime for NAND Flash SSDs

More and more consumer electronics, such as personal computers and smart phones, adopt NAND flash memory as their data storage devices. However, garbage collection (GC) operations in flash memory may degrade both the performance and lifetime for consumer electronics due to the extra page reads and page writes caused by GC. Greedy algorithm, which selects the block with the least valid pages for GC, is usually used for victim block selection so as to reduce page movements. In this paper, to further improve GC performance, we propose a novel caching-aware GC scheme, and its basic idea is to take into account the pages cached in memory so as to further reduce page movements during GC. We also develop a consistent caching scheme to ensure data consistency and revise the victim block selection process with a lightweight caching-aware block selection scheme. We validate the performance of our caching-aware GC on FlashSim, and results show that it improves the performance of SSDs and prolongs their lifetime compared with conventional greedy algorithm.