Quick note,

Installed some HP FlexFabric 5700 switches the other day and I was getting a red LED on the front, and a status message in the CLI

HPE DEV/1/FAN_DIRECTION_NOT_PREFERRED: -Slot; Fan 1 airflow direction is not preferred on slow 1, please check it.

This is a pretty common issue if you chose Back-to-Front fans for your build.

The part numbers for the 5700 series are as follows (taken from this document);

HP 58x0AF Bck(pwr) – Frt(ports) Fan Tray  – JC682A
HP 58x0AF Frt(ports) – Bck(pwr) Fan Tray  – JC683A

The fix is quite simple

To display the airflow configuration;

display fan slot {slot No,}

To change the configuration

Fan prefer-direction slow 1 port-to-power

Below is a screenshot showing the error, the display command and the resolution. Continue reading HP FlexFabric Switches – AirFlow direction is not prefered →