A Workload-Aware-Design of 3D-NAND Flash Memory for Enterprise SSDs

Chao Sun1,  Ayumi Soga2,  Takahiro Onagi2,  Koh Johguchi2,  Ken Takeuchi2
1Chuo Univ./Univ. of Tokyo, 2Chuo Univ.


Solid-state drives (SSDs) have a growing trend of replacing hard disk drives (HDDs) in large computing systems to meet the requirements of power and space. Since 2-dimensional (2D) scaling is facing various limitations, 3D-NAND flash memory architectures have been proposed to maintain the trend of bit density increase and bit cost reduction, which prefers large block and page sizes. However, overly large block and page sizes flash memory harm the throughput of NAND flash devices. Alternatively, storage class memories (SCMs) feature in high speed and low power consumption. By combining SCM, large 3D-NAND flash block and page sizes are acceptable. In this paper, a workload-aware NAND organization design is investigated for enhancing the SSD performance. From the experimental results, a 16MB NAND block size that corresponds to 512 layers and 16KB page size in a 512Gbit P-BiCS 3D-NAND flash memory can be acceptable for applications like financial online transaction processing. Additionally, a large NAND flash page size of 512KB is also acceptable for the relational database etc. applications. With SCM, the acceptable page and block sizes of the 3D-NAND flash memory can be magnified up to 64-times and 4-times, respectively, compared with the SSD composed of only NAND flash memory.