Connectrix: Cisco: System Fan speed showing out of range

Summary: This KB explains why the speed in increasing on the System Fan speed on MDS-9148T switch and how to fix it.

This article applies to This article does not apply to This article is not tied to any specific product. Not all product versions are identified in this article.
Check out other resources

Symptoms

Fan status is good.  
Fan:
-----------------------------------------------------------------------------------------------------------------
Fan             Model                Hw         Status        Airflow direction        Fan Speed[Fan0-Fan1] (rpm)
-----------------------------------------------------------------------------------------------------------------
ChassisFan1     FAN Module 1         --         Ok              Back to Front               2918  -  2133      
ChassisFan2     FAN Module 2         --         Ok              Back to Front               2773  -  2130      
ChassisFan3     FAN Module 3         --         Ok              Back to Front               2320  -  1728      
ChassisFan4     FAN Module 4         --         Ok              Back to Front               2314  -  1754      
Fan_in_PS1      --                   --         Ok              Back to Front                   --
Fan_in_PS2      --                   --         Ok              Back to Front                   --

Below error is seen in Logging Log output: 
2024 Jun 13 08:01:53 bgsansw01 %KERN-0-SYSTEM_MSG: [77978030.873620]  System-Fan-'4' speed is OUT-OF-RANGE. ch1-rpm = '3576',ch2-rpm = '2767', pwm value is '0x99' - kernel
2024 Jun 13 08:01:53 bgsansw01 %KERN-0-SYSTEM_MSG: [77978031.018022]  System-Fan-'3' speed is OUT-OF-RANGE. ch1-rpm = '3661',ch2-rpm = '2805', pwm value is '0x99' - kernel
2024 Jun 13 08:01:53 bgsansw01 %KERN-0-SYSTEM_MSG: [77978031.162912] More than two system fans are absent/ failed. Install good system fans, else switch will shutdown in '180' seconds - kernel

Cause

MDS-9148T System Fans were manufactured by two vendors: Nidec and Delta
Nidec fans run marginally faster than Delta. Hence it occasionally crosses the higher margin of the RPM table.

Resolution

Upgrade to NX-OS 8.4(2f) or later to fix the issue. 

In code 8.4(x), we have increased the margin of the RPM table so that it is for vendor. 

Additional Information

NOTE:
1) Replacing the Fan or swapping the Fan did not fix the issue. 
2) It is not possible to identify from switch logs which vendor fans are used. 

Affected Products

Connectrix MDS 9148T
Article Properties
Article Number: 000226669
Article Type: Solution
Last Modified: 05 July 2024
Version:  1
Find answers to your questions from other Dell users
Support Services
Check if your device is covered by Support Services.