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D-Series Fan Behavior expectations


Userlevel 3
Article ID: 14554

Products
D-Series
D2G124-12, D2G124-12P

Goals
When do the switch cooling fans run?
In the output of a 'show system', does a Fan1-Status or Fan2-Statusof "Not Installed and/or Not Operating" mean that a fan has failed?

Solution
When the unit is powered up, the fans come on at full speed and their operation is checked. Then, if the ambient temperature is below the trip point (11184), the fans are shut back down. After the system fully boots, the fans only cycle on occasionally thereafter, as needed for cooling.

The status of a fan which is not currently spinning - regardless of the reason that it is not spinning - will always read as "Not Installed and/or Not Operating". This is not a sufficient indicator to determine fan failure.

Fan Failure is detected and reported ("FANx-is NOT Functional") when fans should be running (based on software polling of fan-control hardware for the temperature reading, every 30-60 seconds) but one or both fans are not spinning (based on more direct determination of fan operation).

A side-effect of the relatively long temperature-polling interval is that it is possible, during this window of time, to have the fans running but software has not detected it yet (fans running, status "Not Installed..."), or to have the fans no longer running but software has not detected it yet (fans not running, status "Ok").

Note: The D2-PWR and D2-PWR-POE "power supply brick" (10925) fans also may cycle on and off in a similar manner, but their fan status is not manageable.

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