Fan Speed - Extreme Networks 9920 Installation Manual

Fan speed

The following figure shows the rear of the chassis with all five fan modules. Facing the rear, the fan
modules are numbered Fan 1 through Fan 5 from left-to-right. Fan modules are hot-swappable.
Warning
Risk of personal injury
When you remove a fan module, wait for the fans to spin down before you fully withdraw the
fan module. Be careful to keep your fingers out of the fan blades.
Figure 6: View of the fans in the rear of the 9920
Fan speed
There are thermal sensors inside the chassis that monitor the temperature inside the chassis. The
sensors send information regarding temperature readings to the central controller, which automatically
adjusts the fan module fan speed to maintain the proper temperature. For example, when the central
controller determines that the temperature readings of the sensors is decreasing, the fan module fan
speed also decreases. However, if one of the fan modules fails or is temporarily removed, the central
controller increases the speed of the other fan modules to provide maximum cooling to the chassis. The
chassis can operate with a single fan module failure and still maintain uniform airflow across all module
slots. When all fan modules are operational, the central controller, using internal temperature sensors,
determines the speed of the fans.
Warning
Do not operate the chassis for more than a few minutes with a missing fan module. To ensure
internal chassis air pressure is maintained and to avoid interface modules overheating and
shutting down, leave a failed fan module installed until a replacement is available.
Alarms are triggered when the temperature exceeds the following alarm thresholds—Warning, Critical,
and Shutdown.
Note
%d represents a number for either a sensor, slot, or temperature.
The following list shows the log messages for the three threshold types:
•
Warning—Temperature Sensor %d is (%d C) has exceeded the alarm threshold temperature (%d C).
•
Critical—Sensor %d slot %d temperature (%d C) exceeded the critical alarm threshold (%d C).
Module will be shut down at (%d C).
•
Shutdown—Sensor %d in slot %d temperature (%d C) exceeded the shutdown threshold
temperature (%d C). Module has been powered down.
14 9920 Network Packet Broker Hardware Installation Guide
Extreme 9920 Overview