Ethane: An Asymmetric File System for Disaggregated Persistent Memory

The ultra-fast persistent memories (PMs) promise a practical solution towards high-performance distributed file systems. This paper examines and reveals a cascade of three performance and cost issues in the current PM provision scheme, namely expensive cross-node interaction, weak single-node capability, and costly scale-out performance, which not only underutilizes fast PM devices but also magnifies its limited storage capacity and high price deficiencies. To remedy this, we introduce Ethane, a file system built on disaggregated persistent memory (DPM). Through resource separation using fast connectivity technologies, DPM achieves efficient and cost-effective PM sharing while retaining low-latency memory access. To unleash such hardware potentials, Ethane incorporates an asymmetric file system architecture inspired by the imbalanced resource provision feature of DPM. It splits a file system into a control-plane FS and a data-plane FS and designs these two planes to make the best use of the respective hardware resources. Evaluation results demonstrate that Ethane reaps the DPM hardware benefits, performs up to 68× better than modern distributed file systems, and improves data-intensive application throughputs by up to 17×.