This white paper describes a collaborative project that brings together systems software developers, computer vendors, and applications teams to develop hardware and software systems to support scalable I/O for high performance computer systems. The project is organized around the provision of a full-scale testbed for the development and evaluation of new systems software for scalable I/O. In addition, research projects will be formed to address the scalable I/O problem from a number of perspectives, such as languages, compilers, file systems, networking software, persistent object stores, and low level system services.