Firewall Sandwich Dell S4048-ON Switch High Fan Velocity

If operating in an environment with a firewall sandwich and the Dell switches in use are Dell S4048-ON running a firmware version prior to 9.10(0.1P13), a fan speed issue can occur.

In certain scenarios, the fan of the Dell S4048-ON runs at 10000 RPM, even though the temperature is below the upper threshold limit.

This is caused by a known bug in the firmware of the Dell switch.

The solution is to upgrade the switch's firmware to 9.10(0.1P13) or later.  See release notes and information below for more information.

Dell System S4048–ON 9.10(0.1P13) Release Notes

Excerpt from Release Notes: 

PR# 160609 
Severity: Sev 3 
Synopsis: In certain scenarios, the fan runs at 10000 RPM. 
Release Notes: In certain scenarios, the fan runs at 10000 RPM, even though 
the temperature is below the upper threshold limit. 
Workaround: None.