Dear users of the national supercomputing facilities at LRZ, With the installation of the new three Petaflop/s system "SuperMUC" by IBM nearing its completion, we are now starting to prepare for user operation of the system. The LINPACK benchmark has been successfully run, and the results will soon be published at the International Supercomputing Conference (ISC12) in Hamburg; people participating in ISC are cordially invited to the Gauss Centre s booth, where further information will be forthcoming. Also, LRZ s director Prof. Arndt Bode will be speaker of a keynote talk at ISC12, an important topic of which will be the innovations that were developed to enable energy efficient usage of SuperMUC. ISC12 event calendar * Monday 9:00 ISC Opening session with 39th TOP500 list * Thursday 12:00 keynote talk by Prof. Bode on extreme energy efficiency. * Gauss Centre for Supercomputing workshops The Gauss Centre's booth at ISC12 has the number 150. Starting user operation It is presently expected that initial user operation with users selected from large-scale projects will start at the end of June or the beginning of July. These users will be contacted by LRZ approximately one week in advance of being authorized for access. Some time later, LRZ will proceed to ramp up usage until regular user operation will be reached approximately in mid-August. Limitations of early user operation We expect that during early user operation we still need to flush out glitches. Therefore, early users must expect unannounced or very short-term scheduled maintenances. Early users are encouraged to report any observed problems via the LRZ service desk. Differences between SuperMIG and SuperMUC usage * Node architecture: SuperMUC is comprised of 16-way Sandy Bridge nodes; these are equipped with 32 GBytes of main memory much less than the SuperMIG nodes. Due to OS requirements, probably 26 GBytes per node will be available in user space. LRZ will also allow usage of logical hardware threads (SMT/Hyperthreads, enabling use of up to 32 tasks per node), however this resource is also partially used by OS services, and it is very much application dependent whether any performance improvement can be derived from use of SMT. * Code compatibility: It is recommended to rebuild separate executables for use on SuperMUC. While the compilers and basic libraries will be the same as on SuperMIG, the new architecture supports additional instructions (AVX SIMD extension), and IBM has implemented a major new version of the parallel environment (including the MPI library). Both of these may inhibit backward compatibility, and we d like to avoid having to deal with a lot of incidents reporting such (not really solvable) compatibility issues. * File systems: The file systems pointed to by the $SCRATCH and $WORK environment variables will be the new, and vastly larger and better-performing GPFS file systems. The HOME file system will be still shared between SuperMIG and SuperMUC. We will provide additional information on how to transfer data between the non-shared SuperMIG and SuperMUC file systems via the file system documentation. Documentation The LRZ SuperMUC web page will be updated to reflect the changes discussed above. In particular the new LoadLeveler job classes and the file systems will be documented; it may take some time before other parts of the documentation are complete. Courses If you are interested in an introduction on how to use the features and software of the new system, please register for the course "Introduction to SuperMUC" scheduled for the week starting July 2. Specialists from Intel and IBM have been invited to do presentations at this event. This information is also available on our web server http://www.lrz-muenchen.de/services/compute/supermuc/aktuell/ali4325/ Reinhold Bader