Reinforcement Learning-Assisted Management for Convertible SSDs
Qian Wei, Yi Li, Zhiping Jia, Mengying Zhao, Zhaoyan Shen, Bingzhe Li
Abstract
Convertible SSDs, which allow flash cells to convert between different types of flash cells (e.g., SLC/MLC/TLC/QLC), are designed for achieving both high performance and high density. However, previous designs with two types of flash cells encounter a performance cliff degradation once the flash cells of single bit mode are consumed. In this work, we propose a novel level-based convertible SSD (e.g., including SLC-MLC-QLC), named RL-cSSD, that adopts an intermediate layer (e.g., MLC) as a performance cushion. A reinforcement learning-assisted device management scheme is designed to coordinate the data allocation, garbage collection and flash conversion processes considering both the SSD internal status and workload patterns. We evaluated RL-cSSD with various real-world workloads based on simulation. The experimental results show that the proposed RL-cSSD provides 72.98% higher performance on average compared with state-of-the-art schemes.