A Memory-Disk Integrated Non-volatile Memory System with its Dual Buffering Adapter

In this paper, conventional main memory and disk storage layers are merged into a single memory layer using a combination of PRAM and NAND Flash memories, which is called as an integrated memory-disk (IM-D) non-volatile memory structure. The IM-D memory architecture consists of a dual buffering IM-D adapter, an array of SLC/MLC PRAM/Flash hybrid IM-D memory, and an associated memory management module as IM-D access translation layer in the operating system. In this paper, we focus on two hardware modules, i.e., a dual buffering IM-D adapter and an array of PRAM/Flash hybrid IM-D memories. Also, even though non-volatile memories such as PRAM and NAND Flash show advantages in low power consumption, higher density, and non-volatility compared with DRAMs, access latencies of such non-volatile memories are too slow to simply replace conventional DRAMs and disks. Thus, the proposed structure is designed to enhance the lifetime and hide asymmetric read/write access latencies. The experimental results show that overall storage capacity remains the same level and overall access latency decreases by around 49.6 times. Moreover, our structure can significantly save the energy consumption by 83.51%. Based on this result, our proposed memory system offers the possibility of replacing conventional combination of DRAM and HDD/NAND Flash structure based mobile device system with IM-D structure. Keywords-mobile device storage; memory hierarchy; cache and buffering; integrated memory disk structure; dual buffering adapter