UCS 6248 Fabric Interconnect loud fan RPM noise

[Felipe Guimaraes]

Hello,

Our currently installed 6248 Fabric Interconnect pair are generating a loud FAN noise.

Is there any way to reduce theirs RPM? So then can be quieter? The server room have proper air conditioning.

Some logs as bellow:

FABRIC-A(nxos)# show environment fan detail

Fan:
---------------------------------------------------
Module  Fan  Airflow        Speed(%)  Speed(RPM)
             Direction
---------------------------------------------------
1       1    Front-to-Back  60        15428
1       2    Front-to-Back  60        11065
1       3    Front-to-Back  60        14835
1       4    Front-to-Back  60        10997
2       1    Front-to-Back  60        15000
2       2    Front-to-Back  60        11134
2       3    Front-to-Back  60        14835
2       4    Front-to-Back  60        11065

Power Supply:
-----------------------------------
Module  Airflow        Configured
        Direction      Speed (%)
-----------------------------------
1       Front-to-Back  60
2       Front-to-Back  60
FABRIC-A(nxos)#

FABRIC-A(nxos)#
FABRIC-A(nxos)# show environment

Fan:
------------------------------------------------------
Fan             Model                Hw         Status
------------------------------------------------------
Chassis-1       UCS-FAN-6248UP       --         ok
Chassis-2       UCS-FAN-6248UP       --         ok
PS-1            UCS-PSU-6248UP-AC    --         ok
PS-2            UCS-PSU-6248UP-AC    --         ok

Temperature
-----------------------------------------------------------------
Module   Sensor     MajorThresh   MinorThres   CurTemp     Status
                    (Celsius)     (Celsius)    (Celsius)
-----------------------------------------------------------------
1        Outlet     67            58           35          ok

Power Supply:
Voltage: 12 Volts
-----------------------------------------------------------
PS  Model                Input Power       Power     Status
                         Type  (Watts)     (Amp)
-----------------------------------------------------------
1   UCS-PSU-6248UP-AC    AC     780.00     65.00     ok
2   UCS-PSU-6248UP-AC    AC     780.00     65.00     ok

Mod Model                   Power     Power       Power     Power       Status
                            Requested Requested   Allocated Allocated
                            (Watts)   (Amp)       (Watts)   (Amp)
--- ----------------------  -------   ----------  --------- ----------  ----------
1    UCS-FI-6248UP-SUP      492.00    41.00       492.00    41.00       powered-up
3    UCS-FI-DL2             24.00     2.00        24.00     2.00        powered-up

Power Usage Summary:
--------------------
Power Supply redundancy mode:                 Redundant
Power Supply redundancy operational mode:     Redundant

Total Power Capacity                             1560.00 W

Power reserved for Supervisor(s)                  492.00 W
Power currently used by Modules                    24.00 W

                                                -------------
Total Power Available                            1044.00 W
                                                -------------
FABRIC-A(nxos)#

[Bruce Heimlich]

Hi Felipe,

The fan readings that you have posted, do appear to be within the normal range. 60% speed with an RPM range around 15K RPM, is the norm.

What is the actual ambient room temperature? Have you verified that the 6248 Fabric Interconnects have proper clearance within the rack and proper circulation room (not obstructing the fans with cables, etc.)?

The fans on the 6248s are not user adjustable and even if they were, that could potentially create problems, by having the fans run at a slower speed than necessary to properly cool the components.

Thanks.

-Bruce

[Felipe Guimaraes]

Hello Bruce,

The current temperature reading in the server room is 17°C (62.6°F) .

They do have proper front and rear cable clearance. The rack is a Dell 4240 (the front and rear doors are 80 percent perforated).

One thing they have just 1U of clear space bellow then. Do you you think this is enough? or just planed to add more space bellow and above?

[Keny Perez]

Felipe,

Have you tried to just reseat the fans ?   They are how swappable and redundant...

-Kenny

[Felipe Guimaraes]

Hello Kenny,

Just tired that, by the moment I remove one module, the other one doubles the noise. After reseating both fans the problem persists.

[Keny Perez]

Felipe,

It would be a good idea to try Bruce's suggestion too, but first... what is the UCSM version you are running?  I did not see it in the notes...

-Kenny

[Felipe Guimaraes]

Hello Kenny,

UCSM is on Version 2.2(1d)

And the Fabrics are in version:

Kernel  5.2(3)N2(2.21d)
System  5.2(3)N2(2.21d)

[Keny Perez]

Felipe,

Have you had a chance to free up some space around the FIs? 

Is the noise coming out of a particular FI/Fan?  from your description it did not look like, but if yes, it would be a good idea to isolate the issue by swapping the fans.

I am not aware of a particular bug on that version, so please let us know as you might need to open a TAC case.

-Kenny

[Felipe Guimaraes]

So far nothing.

I took advantage of a building power maintenance and with the Fabrics turned off, I swapped the FAN modules. 

I inverted module 1 with module 2 and vice-versa.

After the power was restored, they were quieter for a while, then the noise returned to the previous  annoying levels.

[Keny Perez · Accepted solution]

Felipe,

Please open a TAC case to see if the issue is at the hardware level (a show tech of UCSM will be needed)  an Engineer Failure Analysis MIGHT be needed to determine what is going on.

-Kenny

[Felipe Guimaraes]

UPDATE

I opened a TAC, then after several reviews of the LOGs and huge sh tech files, we concluded that all was normal. This loud noise is normal   and within in normal operational ranges.

However as the server room is not fully acoustics proof and located near production  work desks, we managed to get a RMA for the fan modules for the version 2 modules which are MUCH quieter than V1 due new design.

I have upload both pictures for comparison of the designs.

Thank You!

[Keny Perez]

Felipe,

Any luck making the fans make less noise?

-Kenny

[Bruce Heimlich]

Hi Felipe,

Thank you for that information. Obviously, if you can get more spacing around the Fabric Interconnects, there will be better air circulation.

What Kenny, suggested below, is a good idea but in my experience with this issue, the typical causes tended to be ambient room temperature and or inadequate clearance around the Fabric Interconnects.

Thanks.

-Bruce