NOTE: The CMC monitors the temperature sensors in the chassis and automatically adjust the fan
speed as needed. However, you can override to maintain a minimum fan speed by the racadm
fanoffset command. When overriden using this command, the CMC will always run the fan to the
selected speed even though the chassis does not require the fans to run at that speed.
For more information about the RACADM commands, see the Chassis Management Controller for
PowerEdge VRTX RACADM Command Line Reference Guide available at dell.com/support/manuals.
CMC generates an alert and increases the fan speeds when the following events occur:
• CMC ambient temperature threshold is exceeded.
• A fan stops functioning.
• A fan is removed from the chassis.
NOTE: During updates of CMC or iDRAC firmware on a server, some or all of the fan units in the
chassis rotates at 100%. This is normal.
To view the health status of fans, in the CMC Web interface, do any of the following:
1. Go to Chassis Overview.
The Chassis Health page is displayed. The lower section of chassis graphics provides the left view of
the chassis and contains the health status of the fans. Fan health status is indicated by the overlay of
the fan sub-graphic. Move the cursor over the fan sub-graphic. The text hint provides additional
information about a fan. Click the fan subgraphic to view the fan information in the right pane.
2. Go to Chassis Overview → Fans.
The Fans Status page provides the status, speed measurements in revolutions per minute (RPMs),
and threshold values of the fans in the chassis. There can be one or more fans.
NOTE: In the event of a communication failure between CMC and the fan unit, CMC cannot
obtain or display the health status for the fan unit.
NOTE: The following message is displayed when both the fans are not present in the slots or if
a fan is rotating at a low speed:
Fan <number> is less than the lower critical threshold.
For more information, see the Online Help.
Configuring Fans
Fan Offset — A feature to provide increased cooling to the storage and PCIe regions of the chassis. This
feature allows you to increase the airflow delivery to the HDDs, Shared PERC controllers, and PCIe card
slots. An example usage of the Fan Offset is when you use high-power or custom PCIe cards that require
more cooling than normal. The Fan Offset feature has options of Off, Low, Medium, and High. These
settings correspond to a fan speed offset (increase) of 20%, 50%, and 100% of the maximum speed
respectively. There are also minimum speeds setup for each option, which are 35% for Low, 65% for
Medium, and 100% for High.
Using the Medium Fan Offset setting for example, increases the speed of fans 1–6 by 50% of its maximum
speed. The increase is above the speed already set by the system for cooling on the basis of installed
hardware configuration.
With any of the Fan Offset options enabled, the power consumption will be increased. The system will be
louder with the Low offset, noticeably louder with the Medium offset, and significantly louder with the
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