Michael Reber

HP Proliant Custom FAN Proxy

Project Info

  • Created By Michael Reber
  • Date 2015.03.17
  • Category Custom Build

Project Description

My backup server rack stood for about 5 years at my parents in a small server room which adjoins the living room. Since this was very loud for their location, I designed the HP fan proxy. It is nothing else than a device that reads the FSS (Fan Speed Signal) pin from the server and calculates the speed with a mathematical operation on the arduino (depending on the temperature) the fans should run.

At a speed of 10% - 99% always 30% of the speed is calculated away as far as possible.

The changed FSS is then forwarded to the fans on the signal pin of each fan. The power (12V) and the grounding remain connected directly to the server.

This results in the following scenario:

  • The basic speed is always at 10%. That means 12% speed -> 10%.
  • 20% speed from the server 10% from the proxy.
  • 30% speed from server 10% from proxy
  • 50% speed from server 20% from proxy.

If the server should get too hot and the speed from the server is set to 100%, the Arduino will foreward the  speed directly to the fans until the server sends again a speed below 60%.

So a fast cooling is achieved and a quiet operation can be ensured again.