Revisiting the Architecture and System of Flash-Based Storage

Flash-based storage has been rapidly and widely used in different fields, from embedded systems, desktops, enterprise servers to data centers, in recent years. How to explore the potentials of flash memory is an important research direction in storage research area. Legacy storage systems have been designed for hard disks for more than 60 years, and optimizations to existing systems have limited effectiveness in exploring flash storage benefits. New flash storage architecture and systems by re-architecting flash storage show potentials, and are being adopted in industry. This paper presents the research process in this area. First, it introduces the characteristics of flash memory and solid state drive, and analyses the problems of legacy flash storage architecture. Then, it describes the architecture evolution of flash storage, including device-based FTL, host-based FTL and software managed flash. After the description, it surveys the storage systems respectively on open-channel SSDs and near-data processing, both of which are required for function relocation and cooperation in software-managed flash. Finally, it concludes the challenges and remained research problems.