Is cloud storage ready? Performance comparison of representative IP-based storage systems

摘要

Network based storage systems have traditionally been dominated by Network Attached Storage (NAS) and Storage Area Network (SAN). Cloud based storage systems, including object storage, have gained growing popularity among both private and enterprise users in recent years. Certain enterprises have even considered replacing traditional storage systems with cloud-based systems. Nevertheless, there still lacks a systematic comparative study on the performance of the aforementioned systems to assist such a transition. To fill in this gap, in this paper, we conduct a comprehensive study on the three major network storage systems with realistic network conditions and application behaviours. Specifically, we select one representative from each category for comparison, i.e., Network File System (NFS) from NAS, Internet Small Computer System Interface (iSCSI) from SAN, and OpenStack Swift from cloud storage. As the first study of its kind, we mainly focus on the client-side and take performance as the perspective for comparison. We build a testbed and a suite of micro-benchmarks to study the impact of network complexities and access behaviours on performance. In addition, we employ two widely used macro-benchmarks – PostMark and FileBench – to test the three systems under realistic workloads. Through a set of comprehensive experiments and thorough analysis, we make several key observations. (1) iSCSI excels under good network conditions, e.g., in local area networks (LANs); when network complexities like network delay and packet loss exist, its performance degrades significantly, especially for data-intensive operations. (2) For Internet-like environments, NFS performs poorly, while Swift demonstrates much resilience. (3) Overall, Swift is a viable replacement for NFS in all network scenarios, while it is not ready yet to replace iSCSI for performance-critical environments. (4) System configuration on the client side impacts storage performance significantly and deserves adequate attention. Based on our experimental study, we also make several recommendations to practitioners and pinpoint aspects for system designers to improve each storage system further.