POWER CONDITION DETECTION ON RISC/6000 MODEL 320H

ITEM: RTA000032167



QUESTION:                                                                       
Scenario:  We have a customer who has a 7012-32h that is attached to a          
UPS by only the power cord(no serial cable connection). They recently           
experienced a power surge that was followed by the 7012 issuing a               
message from rc.powerfail saying something to the extent that a power           
surge was detected(or an abnormal power condition). The customer as             
well as myself would like to know how this message was initiated. I'm           
aware the 750 watt power supply found on the 9xx models have this               
detection capability under 3.2.3, but I have found nothing to state that        
this function exists on the 320H model.                                         
Q: Is there a feature we are not aware of that monitors power conditions        
and issues messages when an abnormal condition is detected? If so, is           
it found in 3.2.3 AIX or is it dependant on the power supply type also?         
                                                                                
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ANSWER:                                                                         
 Virtually all of the power supplies for the RISC/6000 series computers         
 have always supported the EPOW signal.  This signal is reflected in the        
 Power Status Register.  With the release of AIX 3.2.3, there is now            
 software that examines this Power Status Register and starts execution         
 of "/etc/rc.powerfail" in the event of a power fault.  "rc.powerfail" is       
 further documented in the file "/usr/lpp/bos/README.powerfail".                
                                                                                
 What I suspect happened in your case is that the UPS detected a power          
 fault and switched to batteries.  During this switch-over, there is a          
 small period of time where the power to the supply in the 320H is              
 interrupted.  The power supply in the 320H detected this and signaled          
 an early power fail signal via the EPOW line.  This signal was recogni zed     
 by the 320H and the kernel sent a SIGPWR signal to init, which in turn         
 called the command on the powerfail line of "/etc/inittab".  The default      
 command is "sh /etc/rc.powerfail > /dev/console 2>&1".                         
                                                                                
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This item was created from library item Q632193      CGTVG                      
                                                                                
Additional search words:                                                        
AUG93 CGTVG CONDITION DETECTION HARDWARE IX MODEL MODELING MODELLING            
POWER RC.POWERFAIL RISC RISCOHW RISCSYSTEM SPIKE SPOOL SUPPLY SURGE             
320H 6000                                                                       
                                                                                
                                                                                
                                                                                
                                                                               


WWQA: ITEM: RTA000032167 ITEM: RTA000032167
Dated: 04/1996 Category: RISCOHW
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