When removing and replacing a server fan module, you must complete the entire removal and replacement procedure within 20 seconds in order to maintain adequate cooling within the system. In anticipation of this time limit, prior to starting the replacement procedure, obtain the replacement fan module and verify that the new fan module is ready for installation. Remove and replace only one fan module at a time.
Fan modules are hot-swappable components, with N+1 fan redundancy. Each fan module contains two complete counter-rotating fans with two fan motors per fan. The four fan motors provide separate tachometer signals so that the fan module reports four tach signals to Oracle ILOM. Even if only one fan is faulted within the fan module, the Oracle ILOM service processor detects that four fans have failed to spin while the fan module is being removed for replacement. If replacing the fan module is not replaced within 20 seconds of removal, Oracle ILOM will take protective action to shut down the system to prevent thermal damage to the system. This is expected behavior.