Lawrence Berkeley National Laboratory

In the next five years, the DOE expects to build systems that approach a petaflop in scale. In the near term (two years), DOE will have several near-petaflops systems that are 10 percent to 25 percent of a peraflop-scale system. A common feature of these precursors to petaflop systems (such as the Cray XT3 or the IBM BlueGene/L) is that they rely on an unprecedented degree of concurrency, which puts stress on every aspect of HPC system design. Such complex systems will likely break current best practices for fault resilience, I/O scaling, and debugging, and even raise fundamental questions about languages and application programming models. It is important that potential problems are anticipated far enough in advance that they can be addressed in time to prepare the way for petaflop-scale systems. This report considers the following four questions: (1) What software is on a critical path to make the systems work? (2) What are the strengths/weaknesses of the vendors and of existing vendor solutions? (3) What are the local strengths at the labs? (4) Who are other key players who will play a role and can help?