To meet enterprise and grand challenge-scale performance and interoperability requirements, a group of engineers-initially ad-hoc but now integrated into the IETF-is designing extensions to NFSv4 that provide parallel access to storage systems. This paper gives an overview of pNFS, an emerging NFSv4 extension that promises file access scalability plus operating system and storage system independence. pNFS bypasses the server bottleneck by enabling direct access to storage by NFSv4 clients and by providing a framework for the co-existence of NFSv4 with other file access protocols. In this paper, we describe an implementation that demonstrates and validates pNFS' potential. The I/O throughput of our prototype matches that of its exported file system and far exceeds standard NFSv4.