Parallel computer architectures require innovative software solutions to utilize their capabilities. This is true for system software no less than for application programs. File system development for the IBM SP product line started with the Vesta research project, which introduced the ideas of parallel access to partitioned files. This technology was then integrated with a conventional AIX environment to create the IBM AIX Parallel I/O File System product. We describe the design and implementation of Vesta, including user interfaces and enhancements to the control environment needed to run the system. Changes to the basic design that were made as part of the IBM AIX Parallel I/O File System are identified and justified.