Large grid installations require global access to massive data stores. Parallel file systems give high throughput within a LAN, but cross-site data transfers lack seamless integration, security, and performance. The GridNFS project, aims to provide scalable, transparent, and secure data management as well as a scalable and agile name space. A key challenge in exporting a parallel file system with NFSv4 is to provide high performance without sacrificing consistency. This paper introduces extensions to the NFSv4 protocol to support parallel access. We implemented a prototype of our design and present experiments demonstrating its scalable architecture.