FT group members Weikuan Yu and Jeffrey S. Vetter, along with Sarp Oral of the NCCS Technology Integration group, will be presenting their paper "Performance Characterization and Optimization of Parallel I/O on the Cray XT" at the 22nd IEEE International Parallel and Distributed Processing Symposium in Miami, Florida. The paper presents an extensive characterization, tuning, and optimization of parallel I/O on the Cray XT supercomputer at Oak Ridge National Laboratory. This characterization covers both data- and metadata-intensive I/O patterns. The authors shed light on the effectiveness of several parallel I/O techniques, such as data sieving and two-phase collective I/O, on the Cray XT. Moreover, the authors have demonstrated that it is possible, and often prudent, to improve the I/O performance of scientific benchmarks and applications by carefully optimizing their application's I/O operations. For example, they show that the I/O performance of the S3D combustion application can be improved at large scale by tuning the I/O system to avoid a bandwidth degradation of 49% with 8192 processes when compared to 4096 processes. For more information see the paper.