Starting user operation of SuperMUC

LRZ aktuell publish at
Di Jul 24 16:56:10 CEST 2012

Our new system SuperMUC has been ranked as No. 4 of the world's fastest
 supercomputers. We will start initial user operation with selected
 projects on July 30, 2012 (10:00 AM). The first projects to access the
 system have been selected from the last Gauss Call and from those which
 recently consume the major part of resources on SuperMIG.
 These users will be contacted by LRZ individually soon. Some time
 later, LRZ will proceed to ramp up usage until regular user operation
 will be reached approximately end of August. We ask all users who gain
 initial access to SuperMUC to be fair by migrating their jobs to the
 new system as fast as possible and thereby removing their job load from
 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 highly 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
   * 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
 The LRZ SuperMUC web page will be updated to reflect the changes
 discussed above. In particular the new LoadLeveler job classes and
 keywords and the file systemss will be documented; it may take some
 time before other parts of the documentation are complete.

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 Matthias Brehm

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