Flash based SSD Aware Parity Logging for Building Reliable Massive Capacity SSDs

Abstract

Thanks to 3D vertical NAND (V-NAND) and quad-level cell (QLC) technology, the storage capacity of flash memory in mobile devices is also increasing very rapidly. Such massive capacity SSDs employ dozens or hundreds of flash memory chips to achieve high performance and large capacity. However, employing plenty of flash chips leads to increased failure rate in SSDs. A RAID-like protection is one of the typical techniques to recover from such failures. With the advent of new types of massive storage devices, studies on the design of RAID-like protection techniques for such huge capacity SSDs are needed. To this end, in this work, we propose a massive SSD-Aware Parity Logging (mSAPL) scheme which protects against n-failures at the same time in a stripe, where n is protection strength from user selection. This technique allows us to choose the data to be protected and the strength of the protection. We implement mSAPL through a trace-based simulator and evaluate both performance and reliability. We show that performance and reliability can be improved compared with the state-of-the-art RAID-like technique.