If surveillance is enabled, the Service Processor provides a 'processor-well' checking function for the node. If a processor fails to perform for a length of time, it is assumed by the Service Processor to be hung. The Service Processor posts an LCD code of 40A00000 or 40B00000. If this occurs, reboot the node and check the AIX error log for hardware errors. If there are hardware errors, call IBM hardware service. Otherwise, collect information using a SNAP tool and call the IBM Support Center.
For more information about surveillance, see the heading "Service processor system monitoring - surveillance" of "Chapter 3, Service procedures" in RS/6000 SP: SMP Thin and Wide Node Service Guide.