Server chronicles - testing fan proposal

The HP ProLiant DL360p Gen8 has 8 fans to cool down the two CPUs and other hardware.

These fans are high speed PWM controlled fan and are prone to fail over time.

The only thing to do is to replace the defective fan with a new one, but it would be nice to understand exactly what the problem is and check if the replacement fan is working before to open the server.

Changing fan

Yesterday I had a fan down and after changed it with a new one, the server refused to restart.

Here some notes :

Location of the fans on the motherboard, fan 1 to the left, fan 8 to the right 

Fortunately changing the fans is a quite simple business, however I strongly suggest to follow this  SPECIFIC procedure to avoid problems :

1. Shut down the server
2. Physically remove power from both the PSU, wait AT LEAST 1-2 minutes before to continue
   This is important to let discharge some components.
3. Identify and remove the failed fan (ILO usually indicate which fan has problems)
4. Install the new fan, be sure is correctly seated and the fan plug  is firmly inserted in the motherboard connector
5. Physically return power to the PSUs
   
   
6. This is critical !  Not following this procedure can cause BIOS errors since the server can retain the memory the failed state !!
   WAIT at least 2-4 minutes to allow the BIOS to start and rescan the hardware.
   DON'T PUSH THE PHYSICAL POWER BUTTON !
7. Login to the ILO
1. Verify the BIOS is OK
2. Verify the Fan redundancy is OK
8. If all is OK, from the ILO, start the server
   
   
9. WAIT UNTIL THE POST COMPLETE THE HARDWARE CHECK !!
   It can take from 3 to 10 minutes, so BE PATIENCE !!!
   
   
10. When the ILO, Fan information shows everything green, the server will start.
    
    
    
    
    

Not following this procedure can bring the server to refuse to boot !!

To reset the server there are different solutions, but typically is enough to  re-follow the procedure above if the server is not restarting after changing the fan.

If not ... google search for the procedure to erase the server NVRAM.

The fan

    The picture on the left shows the typical fan mounted in the server.

    The fan has a 6 pin connector that fit on the motherboard.

    This is the pinout :

Pin 1: Black wire (Ground)

Pin 2: Blue wire (Ground)

Pin 3: Red wire (+12V DC Power)

Pin 4: Yellow wire (Fan Speed/Tachometer)

Pin 5: Not Connected / Empty

Pin 6: Orange/White wire (PWM Control)

So a fan tester should have these blocks :

• DC 12V - xxA power supply
• PWM generation
• Fan speed reading
• Current reading
• safety to remove power on some conditions (too much current, not enough PWM)
• input to change PWM
• display to show : 
• expected speed (in RPM)
• real speed (in RPM)
• fan current usage
• temperature fan