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On a subrack, the temperature is very high because the mode of fan speed control is fanauto

Publication Date:  2012-07-25 Views:  45 Downloads:  0
Issue Description
 On an OptiX OSN 6800 NE, the slave subrack becomes hot under full configuration. A query shows that the temperature of all the boards exceeds 50 degree. The fans only lightly blow and give a hot breeze.
NE version: 5.51.03.22 
 
Alarm Information
Null
Handling Process
1. Check the running indicator of the fan tray. No exception is found.
2. Replace the fan tray with a new one. The fault persists.
3. Query the fan speed. It is found that the fans run at a low speed.
:cfg-get-fan-speed: 22
FAN-SPEED: low
4. Query the mode of fan speed control. It is found that the mode of fan speed control is fanauto.
:cfg-get-fan-speedmode: 22
FAN-SPEED-CTRLMODE: fanauto
5. Set the mode of fan speed control to fantunable. Query the fan speed. It is found that the fans run at a high speed.
:cfg-set-fan-speedmode: 22, fantunable;
:cfg-get-fan-speed: 22;
FAN-SPEED: high
6. Check the fans. It is found that the fans run faster and blow more heavily. The temperature of the subrack and boards lowers. 
 
Root Cause
1. The ventilation on the subrack is poor.
2. Some fans fail.
3. The boards wrongly run. 
 
Suggestions
1. Set the mode of fan speed control to fantunable. The default mode of fan speed control is fanauto. In fanauto mode, the fans cannot automatically control the speed based on the temperature. In fantunable mode, however, the fans can automatically control the speed based on the temperature.
2. It is recommended that the default mode of fan speed control be fantunable on the NEs of any later version.
3. Query the temperature related information in the following ways: 
  To get the temperature of a service board, query the performance of the board. 
  By default, the lower temperature threshold is 0 degree and the upper temperature threshold is 65 degree. To get the temperature thresholds, run the :cfg-get-bdtempth: bid; command.
  To get the current temperature of the SCC, run the :cfg-get-scctemperature command. 
 

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