Ethtool LED identification

True story, a long time ago a small IT department made some changes of personal one of them was the person in charge of the servers. Due to poor administration and organization there was no real documentation of the network and what it was supposed to do. Among the problems found after the change was that none of the racks were labeled or any of the networks device they stored labeled. The new team had to manually log in to every device to see what they were doing.

The routers and switches were the first ones to be identified. However it was a very different to story when it came time to identifying the 56 identical 1U servers and 6 4U SAN’s. Rebooting each server meant down time and an impractical approach. Well, the servers happen to run Linux and one useful tool usually used for setting the duplex on network interfaces came to mind, Ethtool.

Note: you may need to install Ethtool

The solution did not involved down time, but a hands on approach. Ethtool was used to instruct the NIC to flash it’s LED for 5 seconds in a controlled manner.

ethtool -p eth0 5

Let me explain, Ethool will tell the NIC LED on eth0 to flash for 5 seconds. You can change that to a higher number.

30 minutes later and a lot of server watching resulted in proper labeling of every server. Some people need to learn how to use a spread sheet.

  • Good stuff, I recently used Ethtool so that another member of staff could identify and plugin the Ethernet cable to the correct NIC, Thanks Luis.