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Fan Control and Monitoring
Fan Control and Monitoring
The CMM controls the fan speeds and the fan tray LEDs. In a healthy state (no events), the LED is
driven to green color. If any of the fan tray sensors (temperature, voltages, fan tachs) are in an
unhealthy state, the LED is driven to red or amber (red by default).
16.1
Automatic Fan Control
The CMM will drive the fans to full speed (100 percent) under the following condition:
•
An upper critical (major event) or upper non-recoverable (critical event) temperature threshold
is violated in the platform, including blades.
•
If both CMMs are removed from the chassis.
Note: If communication is lost between the CMM and the fantray, it takes approximately two minutes for
the fantray to reset, which will drive the fanspeed to 100 percent.
16.2
Querying Fan Tray Sensors - FantrayN location
To query the fan tray and fan tray sensors, use fantrayN as the location (-l) of the cmmget
command. For example, to query the current RPM value of Chassis Fan 1 in the fantray on the
MPCHC0001 chassis, issue the command:
cmmget -l fantray1 -t "Chassis Fan 1" -d current
16.3
Fantray Cooling Levels
The fantray supports a range of cooling levels that it can operate at. By AdvancedTCA
specification, when queried via IPMI, the fantray returns its maximum cooling level, minimum
cooling level and a recommended cooling level (for normal operation). The AdvancedTCA
specification explains that all fantrays must support all cooling levels between its minimum and
maximum levels by increments of one unit.
The fantray can only run at one cooling level at a time. The cooling level that a fantray is running at
is its current cooling level.
The cooling levels do not represent RPMs because each cooling unit may not actually contain fans.
The CMM Cooling Manager isn't even aware of how the fantrays cool the shelf. It simply knows
that to increase the cooling output of the fantray it should use a higher cooling level. Each fantray
may (and most likely will) have different minimum, maximum and recommended normal cooling
levels.
16.4
CMM Cooling Manager Temperature Status
When in the CMM Control Mode, the Cooling Manger is responsible for changing the fantray's
current cooling level upon temperature events. It does so by switching between four temperature
132
MPCMM0001 Chassis Management Module Software Technical Product Specification
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16
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