FortiSwitch: secure, simple and scalable Ethernet solutions
Article Id 307354
Description The article describes how to evaluate FortiSwitch PSU status and Alarm LED behavior when PSUs are disconnected or fail.
Scope Standalone/Managed FortiSwitch with dual PSU.

FortiSwitch Front panel:





The alarm led is available on the front panel of the FortiSwitch. It has the following led status indicators.

Amber: Fault detected.
Off: No fault detected.


FortiSwitch Back Panel:




The FortiSwitch with the higher series model (like FS448D) will have 2 PSU connections shown above. 

When one of the PSUs is disconnected, no alarm is noticed on the led, and the led status shows 'off'.


Condition for Alarm:

With only one Power PSU, it is not a failure case.

The alarm led is for failure cases like POE over guard band of maximum power budget, or in the case of FAN failed to spin.

How to validate the power supply disconnection:


  1. Run the command 'diagnose sys psu status' on the FortiSwitch (FSW) to check the status of the Power Supply Unit (PSU). The output will indicate the status of each PSU. For example, if PSU1 is connected and operational, it will show a status of 'OK', while if PSU2 is not connected to any power source, it will display a status of 'Not OK'.


diagnose sys psu status

Module Status


  1. If PSU2 was connected and subsequently disconnected, it is possible to verify this action by checking the logs on the FortiSwitch (FSW) using the command 'execute log display'.


    Note that this entry will only appear once and will indicate the change in PSU state to a bad state.

    execute log display

    1: 2024-01-23 17:16:10 log_id=0103036101 type=event subtype=system pri=warning vd=root action="state-change" user="ctrld" ui="None" msg="PS2 changes to bad state


    Some models like the FS112DR with a specific system part have the option to change the behavior of Alarm led functions. For more info refer to the FortiSwitch standalone above v7.4.3.