Hybrid Memory Architecture of PCM and NAND Flash Memories for Enterprise Storage
Ken Takeuchi · 2012
SSDs and emerging storage class non-volatile semiconductor memories (SCM) such as PCRAM, FeRAM, ReRAM and MRAM have enabled innovations in various nano-scale VLSI memory systems for personal computers, multimedia applications and enterprise servers [1]. This paper provides a comprehensive review on state-of-the-art data management technologies of storage class memory and NAND flash memory hybrid solid-state drives (SSDs). A 3D through-silicon-via (TSV)-integrated hybrid PCM/multi-level-cell (MLC) NAND solid-state drives’ (SSDs’) architecture is proposed for PC, server and smart phone applications [1]. NAND-like interface (I/F) and sector-access overwrite policy are proposed for PCM. Furthermore, intelligent data management algorithms are proposed. The proposed algorithms suppress data fragmentation and excess usage of the MLC NAND by storing hot data in the PCM. As a result, 11 times performance increase, 6.9 times endurance enhancement and 93% write energy reduction are achieved compared with the conventional MLC NAND SSD. Both PCM write and read latency should be less than 3us to obtain these improvements. The required endurance for PCM is 10k cycles. 3D TSV interconnects reduce the energy consumption by 68%.