Fans in 3820 720 stream constantly run at high speed with lot of noise

Asset ID:	1-71-2114204.1
Update Date:	2018-03-20
Keywords:

Solution Type Technical Instruction Sure

Solution 2114204.1 : Fans in 3820 720 stream constantly run at high speed with lot of noise

Applies to:

Acme Packet 3820 - Version S-Cz7.1.5 and later
Information in this document applies to any platform.

Goal

Customer reported that fans constantly run at high speed with lot of noise. They were using 3820 SBC with nnSCZ720m2.32.bz version.

Fan RMA didn't help.

║ @ ACMESYSTEM# show fans
║ @ MAIN FAN1: +15300.000 RPM
║ @ MAIN FAN2: +15300.000 RPM
║ @ MAIN FAN3: +15300.000 RPM
║ @ MAIN FAN4: +15300.000 RPM
║ @ .
║ @ ACMESYSTEM# show temperature
║ @ CPU TEMP0 +47.750 C (high = +100.000 C)
║ @ MAIN TEMP0 +25.000 C (high = +100.000 C)
║ @ MAIN TEMP1 +23.500 C (high = +100.000 C)
║ @ PHY TEMP0 +25.500 C (high = +100.000 C)
║ @ PHY TEMP1 +25.500 C (high = +100.000 C)
║ @ PHY FPGA TEMP0 +28.000 C (high = +100.000 C)
║ @ PHY TCM0 +30.500 C (high = +80.000 C)

Solution

This is observed specific to 3820 platform using 720 stream. When checked with engineering, they informed that 3820 fans are supposed to be running at a max speed which is in this case, as neither the driver nor the user space provide any kind of speed control. This is as per design.

Engineering is worked on mimicing the fan control behavior like as in 6.x releases. The fix is included in the SCZ720m6p7 SCZ730m2 ECZ730m2p4 and onward GA releases.

Kindly check the defect 21636074 for further information.

References

<BUG:21636074> - WHEN UPGRADING TO NNSCZ720M3, EXCESS FAN NOISE

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