With this second issue of "High Performance Computing on Vector Systems ~ Proceedings of the High Performance Computing Center Stuttgart" we con tinue our publication of most recent results in high performance computing and innovative architecture. Together with our book series on "High Perfor mance Computing in Science and Engineering'06 - Transactions of the High Performance Computing Center Stuttgart" this book gives an overview of the most recent developments in high performance computing and its use in scientific and engineering applications. This second issue covers presentations and papers given by scientists in two workshops held at Stuttgart and Tokyo in spring and summer 2006. These workshops are held as part of a collaboration of NEC and HLRS in the "T- aflop Workbench Project" and many of the papers stem from users of the large NEC SX~8 vector systems installed at Stuttgart. At the forefront of research has been the question of how to achieve a high level of sustained performance on vector supercomputers.