Supporting Transactions for Bulk NFSv4 Compounds

Abstract

More applications nowadays use network and cloud storage; and modern network file system protocols support compounding operations---packing more operations in one request (e.g., NFSv4, SMB). This is known to improve overall throughput and latency by reducing the number of network round trips. It has been reported that by utilizing compounds, NFSv4 performance, especially in high-latency networks, can be improved by orders of magnitude. Alas, with more operations packed into a single message, partial failures become more likely---some server-side operations succeed while others fail to execute. This places a greater challenge on client-side applications to recover from such failures. To solve this and simplify application development, we designed and built TC-NFS, an NFSv4-based network file system with transactional compound execution. We evaluated TC-NFS with different workloads, compounding degrees, and network latencies. Compared to an already existing NFSv4 system that fully utilizes compounds, our end-to-end transactional support adds as little as ~1.1% overhead but as much as ~25× overhead for some intense micro- and macro-workloads.