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[SRX] Fan spin speed shows normal even when temperature alarm is raised

  [KB34132] Show Article Properties


Summary:

This article describes the behavior of the fan speed staying normal when a yellow temperature alarm is raised on SRX340 and SRX345.

Symptoms:

CLI command 'show chassis temperature-thresholds' displays temperature threshold of SRX340 and SRX340.

root> show chassis temperature-thresholds
                           Fan speed      Yellow alarm      Red alarm      Fire Shutdown
                          (degrees C)      (degrees C)     (degrees C)      (degrees C)
Item                     Normal  High   Normal  Bad fan   Normal  Bad fan     Normal
Chassis default              35    45       50       40       75       65      100
Routing Engine               35    45       50       40       75       65      100

In the following release, when chassis temperature increases over 50 degrees Celsius, a yellow alarm will be generated. 

  • 15.1X49-D170 and earlier releases
  • 17.4R2 and earlier releases
  • 18.1R3 and earlier releases
  • 18.2R2 and earlier releases
  • 18.3R2 and earlier releases
  • 18.4R1
  • 19.1R1
root>show system alarm
1 alarms currently active
Alarm time               Class  Description
2019-03-12 19:41:36 UTC  Minor  Host 0 Temperature Warm

But the fan speed will not be changed to high:

root> show chassis environment no-forwarding
Class Item                           Status     Measurement
Temp  Routing Engine                 OK         51 degrees C / 123 degrees F
      Routing Engine CPU             OK         87 degrees C / 188 degrees F
Fans  SRX340 Chassis fan 0           OK         Spinning at normal speed
          SRX340 Chassis fan 1       OK         Spinning at normal speed
          SRX340 Chassis fan 2       OK         Spinning at normal speed
          SRX340 Chassis fan 3       OK         Spinning at normal speed
Power Power Supply 0                 OK
Cause:

Fan speed and yellow alarm threshold for SRX340 and SRX345 was modified in 15.1X49-D70 release. But this modified threshold value was not reflected in the CLI command output.

Correct threshold value is:

​root> show chassis temperature-thresholds
                           Fan speed      Yellow alarm      Red alarm      Fire Shutdown            
                          (degrees C)      (degrees C)     (degrees C)      (degrees C)            
Item                     Normal  High   Normal  Bad fan   Normal  Bad fan     Normal            
Chassis default              35    56       60       40       75       65        100            
Routing Engine               35    56       60       40       75       65        100     
Solution:

This is a cosmetic display issue.

Even though the fan speed threshold in CLI command output is showing wrong threshold value, fan speed will increase when temperature reaches over 56 degrees Celsius.

The CLI command output is corrected in following releases.

  • 15.1X49-D180
  • 18.2R3
  • 18.3R3
  • 18.4R2
  • 19.1R2
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