More Than Capacity: Performance-oriented Evolution of Pangu in Alibaba

This paper presents how the Pangu storage system continuously evolves with hardware technologies and the business model to provide high-performance, reliable storage services with a 100-microsecond level of I/O latency. Pangu’s evolution includes two phases. In the first phase, Pangu embraces the emergence of the solid-state drive (SSD) storage and remote direct memory access (RDMA) network technologies by innovating its file system and designing a user-space storage operating system to substantially reduce the I/O latency while providing high throughput and IOPS. In the second phase, Pangu evolves from a volume-oriented storage provider to a performance-oriented one. To adapt to this change of business model, Pangu upgrades its infrastructure with storage servers of much higher SSD volume and RDMA bandwidth from 25Gbps to 100Gbps. It introduces a series of key designs, including traffic amplification reduction, remote direct cache access, and CPU computation offloading, to ensure Pangu fully harvests the performance improvement brought by hardware upgrade. Other than introducing these technology innovations, we also share our operating experiences during Pangu’s evolution, and discuss important lessons learned from them.