pNFS and Linux: Working Towards a Heterogeneous Future

Heterogeneous and scalable remote data access is a critical enabling feature of widely distributed collaborations. Parallel file systems feature impressive throughput, but sacrifice heterogeneous access, seamless integration, security, and cross-site performance. Remote data access tools such as NFS and GridFTP provide secure access to parallel file systems, but either lack scalability (NFS) or seamless integration and file system semantics (GridFTP). Anticipating terascale and petascale HPC demands, NFSv4 architects are designing pNFS, a standard extension that provides direct storage access to parallel file systems while preserving operating system and hardware platform independence. pNFS distributes I/O across the bisectional bandwidth of the storage network between clients and storage devices, removing the single server bottleneck so vexing to client/server-based systems. Researchers at the University of Michigan are collaborating with industry to develop pNFS for the Linux operating system. Linux pNFS features a pluggable client architecture that harnesses the potential of pNFS as a universal and scalable metadata protocol by enabling dynamic support for layout format, storage protocol, and file system policies. This paper evaluates the scalability and performance of the Linux pNFS architecture with the PVFS2 and GPFS parallel file systems.