Exploiting data longevity for enhancing the lifetime of flash-based storage class memory

Abstract

This paper proposes to exploit the capability of retention time relaxation in flash memories for improving the lifetime of an SLCbased SSD. The main idea is that as a majority of I/O data in a typical workload do not need a retention time larger than a few days, we can have multiple partial program states in a cell and use every two states to store one-bit data at each time. Thus, we can store multiple bits in a cell (one bit at each time) without erasing it after each write -That would directly translates into lifetime enhancement. The proposed scheme is called Dense-SLC (D-SLC) flash design which improves SSD lifetime by 5.1×-8.6×.