Extending the Lifetime of Object-based NAND Flash Device with STT-RAM/DRAM Hybrid Buffer

A major limitation of NAND flash memory is erase-before-program characteristics. It incurs write amplification, severely degrading system performance and endurance. Previous works reveal that metadata update substantially contributes to write amplification in object-based NAND flash device (ONFD). To further reduce the overhead of metadata update in ONFD, we propose a hybrid buffer scheme (HBS) by utilizing the lower latency and byte-addressable characteristics of the promising emerging non-volatile memory STT-RAM. Our HBS proposes to store ONFD metadata with highest cost in a complement STT-RAM buffer to reduce write amplification. Considering limited size of STT-RAM, we propose a hybrid buffer management technique to maximize effective memory utilization. In addition, by leveraging non-volatility of STT-RAM, our HBS can also substantially reduce data recovery overhead and complexity upon power failure. Experiment results show that the proposed design can achieve up to 15% performance improvement with average 34% endurance extension compared to the state-of-the-art works.