Installation guide

Brocade FastIron SX Series Chassis Hardware Installation Guide 83
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Managing the cooling system
4
Automatic mode
By default, the fans operate in automatic mode, self-adjusting their speed based on both of the
following factors:
• The current temperature of each thermal plane
• The current configured temperature threshold ranges for all fan speeds
The Brocade device has default temperature threshold ranges for fan speeds (Table 24). If desired,
you can change these settings.
The software regularly polls the chassis to obtain the temperature of each thermal plane, then
uses this information to decide whether or not to switch the fan speed. By default, the Brocade
device polls the chassis every 60 seconds for temperature data. You can change this interval using
the CLI command chassis poll-time.
If the temperature of a thermal plane exceeds the high temperature level of the temperature range
associated with the current fan speed in the associated plane, the system will switch the fan speed
to the next higher level. For example, the current fan speed is 3 (medium), and the configured
operating temperature range for fan speed 3 is 40 to 50 degrees Centigrade for Thermal Plane 2.
Based on this configuration, if the temperature of Thermal Plane 2 rises to 51 degrees Centigrade,
the system will automatically increase the fan speed to fan speed 4.
Manual mode
Typically, the fans operate in automatic mode, as described above. If desired, you can manually set
the speed at which the fans will operate. For more information, refer to “Manually setting the fan
speed” on page 87.