System X: building the Virginia Tech supercomputer

System X was conceived in March 2003, designed in July 2003, and by October it had achieved a sustained performance of 10.28 Teraflops, making it the third fastest supercomputer in the world today. System X has several novel features. First, it is based on an Apple G5 platform with the new IBM PowerPC 970 64-bit CPUs. Secondly, it uses a high performance switched communications fabric called Infiniband. Finally, system X is cooled by a hybrid liquid-air cooling system. In this paper, the author presents the motivation for System X, its architecture, and the challenges faced in building, deploying, and maintaining a large-scale supercomputer. The paper is focused on transparent fault tolerance for massively parallel supercomputers, scalable network emulation, compiler directed strategies for flexible data sharing models, and routing algorithms for backbone IP networks