DAC: Dedup-assisted compression scheme for improving lifetime of NAND storage systems

Thanks to an aggressive scaling of semiconductor devices, the capacity of NAND flash-based solid-state-drives (SSDs) has increased greatly. However, this benefit comes at the expense of a serious degradation of NAND device's lifetime. In order to improve the lifetime of flash-based SSDs, various data reduction techniques, such as deduplication, lossless compression, and delta compression, are rapidly adopted to SSDs. Although each technique has been extensively studied, efficiently combining these techniques in a synergistic fashion was not thoroughly investigated. In this paper, we propose a novel dedup-assisted compression (DAC) scheme that integrates existing data reduction techniques so that potential benefits of individual ones can be maximized while overcoming their inherent limitations. By doing so, DAC greatly reduces the amount of write traffic sent to SSDs. DAC also requires negligible resources by utilizing existing hardware modules. Our evaluation results show that the proposed DAC decreases the amount of written data by up to 30% over a simple integration of deduplication and lossless compression.