Nehalem cluster update

OS upgrade on hww nehalem cluster will take place on August 14th 2012 9:00 till 18:00.

• The HOME will be changed to the same fileserver as the Cray XE6 system. Users have to migrate data on their own, Cray users should be careful not to damage existing data.
• Users can access the new HOME on the frontend systems cl3fr1 and cl3fr2 under /zhome/academic/… from now on to migrate data
• The old HOME-Directory is available till September 30st 2012. To access your old HOME Directory a script “get_old_HOME_path” will be provided. The old HOME Filesystems will be mounted read only on the frontend servers only, not on the compute nodes.
• OS will be changed from Redhat 5.3 compatible to Redhat 6.2 compatible scientific linux versions
• Names and versions of available module files have to be checked after upgrade, as those can differ – existing job scripts loading modules can fail after upgrade if not adjusted, as not all old modules are maintained with new version.
• We observe slight performance regressions with MPI codes if no CPU binding is used with new os -> please use your MPIs pinning/binding options
• After this upgrade, new node types “mem256gb” and “sb” are available. “mem256gb“ is 4 socket 256GB 48 core AMD interlagos systems, “sb” is 2 socket 32GB 16 core (32 threads) intel Sandy Bridge systems. To achieve best performance with the later systems, use AVX switches of your compiler.

If your HOME directory has not been created you might not have provided the appropriate forms to access HLRS computing systems.

Bundesprojekte (Federal Projects) have to provide a form for the whole project. This form has been made available to all relevant projects by email.

Universitätsprojekte (Stuttgart University Projects) have to provide a form to be completed by the institute. Please ask the institut's contact person for more information.

In addition, all users have to complete and sign the form "Antrag auf Zulassung zur Nutzung der Rechenanlagen des HLRS" which is available from your HLRS contact person or from the respective project supervisor.