Fan speed on x440-48p at 11000 RPM


I have a stack of Summit x440-48p switches running XOS 15.3.4.6 patch1-14. They are in a sizable cabinet in a standard office area and I would have thought the temperature and fans would be normal, but the fans are all at 11000 RPM for both switches:
sh fans

FanTray-1 information: State: Operational NumFan: 4 Fan-1: Operational at 11000 RPM Fan-2: Operational at 11000 RPM Fan-3: Operational at 11000 RPM Fan-4: Operational at 11000 RPM FanTray-2 information: State: Operational NumFan: 4 Fan-1: Operational at 11000 RPM Fan-2: Operational at 11000 RPM Fan-3: Operational at 11000 RPM Fan-4: Operational at 11000 RPM FanTray-3 information: State: Empty FanTray-4 information: State: Empty FanTray-5 information: State: Empty FanTray-6 information: State: Empty FanTray-7 information: State: Empty FanTray-8 information: State: Empty[/code]Additionally, the temp of the switches is:
sh temperature Field Replaceable Units Temp (C) Status Min Normal Max --------------------------------------------------------------------------- Slot-1 : X440-48p 34.50 Normal -10 0-48 55 Slot-2 : X440-48p 34.00 Normal -10 0-48 55 Slot-3 : Slot-4 : Slot-5 : Slot-6 : Slot-7 : Slot-8 :[/code]While 92 F or so is not cool, it seems well below the Normal range about 24 degrees F. Is it normal for these fans to be so noise and at 11000 RPMs at this temp?

6 replies

Userlevel 6
The 440 is a little unique in how it manages its fans....

Here's a GTAC Knowledge Article that provides an explanation:
https://gtacknowledge.extremenetworks.com/articles/Q_A/On-a-X440-the-fan-speed-is-always-listed-as-1...
That is helpful in understanding how the x440 switch works, but I think the issue in my case is actually that the fans are on full speed and it's loud as it's deployed near office work space in a closed cabinet that just so happens to be hot enough to make them spin faster. What temp does it have to be below for the fans to run quietly...it seems to be around 34C, is that right?
Userlevel 7
Hi Nathan,

Essentially, if the temperature is below 30C the switch will run its fans at half speed (or the fans will be off in the 24 port non-PoE variants of the X440). Once the temperature exceeds 30C, the fans will run at full speed. I've updated the article that Ryan linked earlier with the specifics for each X440 model.

https://gtacknowledge.extremenetworks.com/articles/Q_A/On-a-X440-the-fan-speed-is-always-listed-as-1...

-Brandon
Userlevel 6
Brandon Clay wrote:

Hi Nathan,

Essentially, if the temperature is below 30C the switch will run its fans at half speed (or the fans will be off in the 24 port non-PoE variants of the X440). Once the temperature exceeds 30C, the fans will run at full speed. I've updated the article that Ryan linked earlier with the specifics for each X440 model.

https://gtacknowledge.extremenetworks.com/articles/Q_A/On-a-X440-the-fan-speed-is-always-listed-as-1...

-Brandon

Nice 440 fan behavior summary table Brandon.

Really like the GTAC Knowledge article improvement based on Nathan's questions here. Good stuff!
So, am I understanding this correctly? Even if the temperatures drop below 30C, they are reported as, "Operational at 11000 RPM?"

WWTP_24p_1.1 # show temp
Field Replaceable Units Temp (C) Status Min Normal Max
---------------------------------------------------------------------------
Switch : X440-24p 29.50 Normal -10 0-48 55
WWTP_24p_1.2 # show fan

FanTray information:
State: Operational
NumFan: 4
Fan-1: Operational at 11000 RPM
Fan-2: Operational at 11000 RPM
Fan-3: Operational at 11000 RPM
Fan-4: Operational at 11000 RPM
WWTP_24p_1.3 #

WWTP_24p_2.3 # show fan

FanTray information:
State: Operational
NumFan: 4
Fan-1: Operational at 11000 RPM
Fan-2: Operational at 11000 RPM
Fan-3: Operational at 11000 RPM
Fan-4: Operational at 11000 RPM
WWTP_24p_2.4 # show temp
Field Replaceable Units Temp (C) Status Min Normal Max
---------------------------------------------------------------------------
Switch : X440-24p 25.50 Normal -10 0-48 55
WWTP_24p_2.5 #

One of these is in an office area, so I sure would like them to slow down!
Userlevel 3
Hello Kurt,

For the X440 platforms we have 3 temperature sensors:
  1. ambient for fan control
  2. ambient for EXOS temperature reporting
  3. hot-spot for EXOS debugging
EXOS cannot read or display the value of the fan control temperature sensor (1). The temperature reported by EXOS is separate from the fan controller, therefore the temperature reported by EXOS may not align to the fan off/on, low speed/high speed behavior.

Fan Status includes Fail and Ok for the set of fans. Fan status can be reported with “show fan". Fan speed cannot be checked as the X440 has no fan controller component.

The data that is displayed within “show temperature” is from sensor 2:

(debug) X440-24p.3 # show temperature
Field Replaceable Units Temp (C) Status Min Normal Max
---------------------------------------------------------------------------
Switch : X440-24p 28.00 Normal -10 0-48 55

With EXOS debug-mode enabled, we can view the data from both sensors 2 and 3:

(debug) X440-24p.4 # !cat /proc/extr/temp
Number of temperature sensors=2
Sensor 0) Module=Motherboard(2), type=default(1), 28.00 # sensor 0 is 2 in the above list
Sensor 1) Module=Motherboard(2), type=Hotspot(3), 41.50 # sensor 1 is 3 in the above list

What is the HOTSPOT temperature?
  • Apart from default switch temperature sensor, switch will have additional sensor internally and it seems like that internal sensor has reached maximum temperature under normal working conditions. The switch has got a hotspot temperature and it placed internally near to the units which exhibits high temperature reading. By reading the hotspot temperature, the fan will start running and report has 11000RPM.
Note:- We would require debug-mode access to collect the above mentioned outputs.

For the X440-24p (it’s not the same for all X440 models) if the fan control temperature sensor is below 30C the fan speed should be 5900 RPM (half-speed). If the fan control temperature sensor is above 30C the fan speed should be 11000 RPM (full-speed).

Please find below the fan working behavior on Summit X440-48P/T port switches:
  • The X440-48P/T port switch fans operate at either high-speed (above ~30C) or low-speed (below ~30C). The fan speed is entirely controlled by hardware.
  • The fan speed (i.e. RPM) is not reported to software, nor does the hardware provide any indication to software in what mode (high- or low-speed) the fans are operating.
  • The only fan status indication hardware provides to software is a FAN-FAIL signal. This informs software that the fan(s) are either not spinning at all, or they are spinning at a very low (failing) speed.
  • Therefore, the only thing software knows about the fans is whether they have failed or not. So in consideration of this, software only reports that the fans are on (running full-speed/not failed) or off (failed).
  • We have confirmed this in our internal lab testing with X440-48P/T port switch running in hot chamber. We could see that the software reports fans operational with speed 11000RPM at temperature below and above 30c. It is a product design limitation.
The Summit X440-24t devices have different fan working behavior.

In your scenario,I suspect the HotSpot Temperature can be above ~30C. So, the fans are running in 11000 RPM (high speed). We could collect the outputs from these switches to verify the status.

If you need more information, please do not hesitate to contact us or open a GTAC case.

Regards,
Ram

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