Cloud Storage Acceleration Layer (CSAL): Enabling Unprecedented Performance and Capacity Values with Optane and QLC Flash

Cloud service providers offer a range of storage services to enterprises, such as block storage and object storage. Currently, more data is being created, stored, and analyzed than ever before. Cloud service providers tend to extend storage capacity to meet the requirement of high-growth technologies, such as big data analytics, real-time databases, and high-performance computing. All these technologies require not only high performance but also ever-expanding data volumes. Ongoing advantages of high-density NAND flash enable both large capacity and high performance, which meets the requirement of ever-expanding data volumes. However, the endurance and write performance of NAND flash are decreasing to the point that Penta-level cell (PLC) media can neither sustain random workloads nor match the line rates of faster networks. Therefore, the key gap in building NAND-based storage systems is the ever-decreasing write performance per TB and endurance. We propose CSAL, a Flash Translation Layer (FTL) in Storage Performance Development Kit (SPDK), for new types of media tiers with Intel® Optane™ and QLC Flash. CSAL utilizes high performance and endurance Intel® Optane™ media as thin performance tier to accelerate QLC NAND flash as capacity tier. The key insight of CSAL is to leverage Intel® Optane™ media to shape random user writes to NAND-friendly writes. CSAL not only eliminates internal fragmentation of the NAND SSDs but also absorbs frequently updated user writes in the Intel® Optane™ tier thus improving system-level endurance. Cloud tenants usually have different I/O behaviors, which causes more complex I/O patterns in cloud storage resulting in performance degradation and unpredictability. In this presentation, we will show and analyze the real-world I/O behaviors from the big data services of Alibaba Cloud. And demonstrate how we provide stable and predictable performance for cloud storage services with CSAL and Intel® Optane™ technologies.