H132397.TXT - SERVER 500 MICROCHANNEL RAID DRIVES DDD, CABLE INSTRUCTIONS      
                                                                                
 SYMPTOM:                                                                       
 A single drive failed, but 2 RAID fixed disk drives appear                     
 as DDD (Defunct, the drive is not responding to commands).                     
 Routine recovery procedures are ineffective in bringing the                    
 DDD drive(s) back on-line.                                                     
                                                                                
 Note: This tip is for the MicroChannel RAID adapter.  For the                  
       PCI RAID adapter, refer to Record H133382.                               
       The system may have run without problems for some time.                  
                                                                                
 PROBLEM ISOLATION AIDS:                                                        
 - The system is a Server 500 or 520 RAID Array (8641) with a                   
   MicroChannel SCSI-2 F/W Streaming RAID adapter installed.                    
 - More than one DASD Backplane installed.                                      
 - The system diagnostics do not fail.                                          
 - The RAID Administration program appears normal.                              
                                                           Sel #     7 of     7 
 Also refer to Record H131887 regarding multiple DDD disks.                     
                                                                                
 FIX:                                                                           
 Background:                                                                    
 The MicroChannel RAID adapter requires two cables attached                     
 to the DASD backplane in order to maintain control of the                      
 RAID subsystem, the SCSI signal cable (wide), and a much smaller               
 Status cable.  The Backplane in Bank C must be attached to                     
 SCSI edge Connector Channel 1.  The DASD backplane in Bank D                   
 would be attached to SCSI edge Connector Channel 2.  The same is               
 true of the Status cables.  Status connector 1 must be attached                
 to DASD Backplane C and Status connector 2 must be attached to                 
 DASD Backplane D, if installed.                                                
                                                                                
 On the RAID Adapter installed in the Server 500, the signal                    
 cable (FRU P/N82G3613) and Status cables (FRU P/N06H5081)                      
                                                           Sel #     7 of     7 
 for each channel may not be connected to the same backplane.                   
 (For example: The Status cable for the Backplane in BanK C is                  
 mistakenly connected to Bank D, and vice-versa).  In this case,                
 the RAID Adapter is not communicating with the correct Backplane               
 (but has no way of knowing this), so erroneous status                          
 information is being presented to the RAID Adapter.                            
                                                                                
 Attempting to rebuild a fixed disk with the cables mis-                        
 connected in this manner will probably result in customer data                 
 loss.                                                                          
                                                                                
 In systems which have more than one DASD Backplane installed,                  
 make certain that the RAID Channel 1 (SCSI) signal cable and the               
 RAID Channel 1 Status cable are both attached to the same                      
 Backplane (are not crossed).                                                   
     SCSI-2 Fast/Wide Streaming RAID Controller, FRU P/N06H3059                 
                                                               |                
 ____DASD STATUS CONN._______  _________  __  __________  _____|                
 | |   ___  ___              ||Channel 1||  |_|Channel 2||     |                
 | |  |___||___|                          ______   _______     ||               
 | |  Chan1 Chan2   ______  ________     |      | |       |    ||               
 | |         ______ |     | |      |     |      | |       |    ||               
 | |         |    | |     | |      |     |      | |       |    ||               
 | |         |    | |     | |      |     |______| |_______|    ||               
 | |         |____| |_____| |______|                           ||               
 |_|_____________________              _           _______     |                
                        ||||||||||||||| |||||||||||       |____|                
                                                               |                
                                                                                
 Note: The HMM (Hardware Maintenance Manual) S52G-9971-02, and                  
 The PC 500 User's Manual do not show the identification of                     
 the DASD Status Connectors, as shown above.                                    
                                                                                
 Note: While the SERVER 500 and the Server 720 both use the                     
 same RAID controller and a similar Backplane, there is no Status               
 Cable attached directly to the RAID Controller in the Server                   
 720.  In the Server 720, the Status Cable on the Backplane is                  
 daisy-chained to the Controller Card mounted behind the operator               
 power sequence panel.  The RAID controller communicates to the                 
 DASD Backplane through the micro channel bus, the system board                 
 and the Controller Card.  In the Hardware Maintenance Manual                   
 Supplement for the Server 720 (S30H-2352-00) page 29, index 1,                 
 this status cable is called the System Status Cable,                           
 FRU P/N82G3617.                                                                
                                                                                
 April 26, 1996