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 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 malfunctioning and after I 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 

Changing the fans is a quite simple operation, 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 of the previous 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 HAVE PATIENCE !!!
   
   
10. When the ILO, Fan information shows everything green, the server will start.
    
    
    
    
    

Not following this procedure can bring the server in a state where it 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.

The connector has a 2 mm pitch rather than the standard 2.54, on two rows (2 x 3) compatible with the  JST series, but I found on Adafruit a nice adapter that convert the pitch from 2 mm to 2.54 mm (IDC Breakout Helper - 2x3 (6 pin) ).
That should allow to easily set up a board where to connect the fan under test.

CAUTION !!!
Until tested the pinout below COULD BE WRONG !
HP is not exactly advertise proprietary pinout.

Currently I did not yet tested this pinout !!!

This is the pinout (note that the wires on the fan could be covered by tape) :

Pin 1: Red Wire (+12V DC Power - bridget with pin 3)

Pin 2: Black wire (Ground - bridget to pin 6)

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

Pin 4: Yellow wire (Fan Speed/Tachometer)

Pin 5: Blue wire (PWM control)

Pin 6: Black wire (Ground) 

So a fan tester should have these blocks :

• DC 12V - 2A power supply (the nominal current for a fan is around 1.10 A)
• 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

The fan tester should power the fan under test, measure the RPM with different speed settings and compare the reads done with the expected results.

Testing a working/new fan is possible to capture some values and use them as referral.