Software controlled cell bit-density to improve NAND flash lifetime

Abstract

Hybrid flash architectures combine static partitions in Single Level Cell (SLC) mode with partitions in Multi Level Cell (MLC) mode. Compared to MLC-only solutions, the former exploits fast and short random writes while the latter brings large capacity. On the whole, one achieves an overall tangible performance improvement for a moderate extra cost. Yet, device lifetime is an important aspect often overlooked. In this paper, we show how a dynamic SLC-MLC scheme provides significant lifetime improvement (up to 10 times) at no cost compared to any classic static SLC-MLC partitioning based on any state of the art Flash Translation Layer policy.