Description

This article provides information on how to isolate the cause of the fan failure issue.

Symptoms

There is an Alarm "FAN not spinning" reported as below,

Snap:

user@switch> show chassis alarms
1 alarms currently active
Alarm time Class Description
2023-06-28 05:04:04 UTC Major FPC 0 Fan 1 not spinning

Solution

The following syslog message and alarm are generated:

Sep 17 17:44:20  EX-box chas[900]: Fan 2 is NOT spinning correctly
Sep 17 17:44:20  EX-box craftd[920]:  Major alarm set, FPC 0 Fan 2 not spinning
Sep 17 17:44:20  EX-box alarmd[917]: Alarm set: FAN JAVA color=RED, class=CHASSIS, reason=FPC 0 Fan 2 not spinning

manager@FS23-04> show chassis alarms 
1 alarms currently active
Alarm time               Class  Description
2011-09-17 17:44:20 JST  Major  FPC 0 Fan 2 not spinning
In this state, you cannot evaluate which FRU has a defect. This message and alarm indicates that the kernel is unable to get the fan speed correctly from the register via chassism. So, it means that you cannot decide whether the fan or chassis has a defect.

Workaround 1:-
Power-cycle the box

If Workaround 1 doesn't help, perform the following procedure:
  1. Physically check physically if the fan is not spinning or it is a false alarm.
  2. Check by swapping the fan tray with a known good one to check if the issue is actually with the fan tray.
  3. If swapping the fan tray with a known good one still does not resolve the issue, then the fault can be with the fan slot/chassis.
  4. If the switch has built-in FAN[Example: EX2300] reports this Alarm, power-cycle the switch, if not recovered it is fault with the switch

Modification History

2020-07-18: Article reviewed for accuracy; minor non-technical edits.
2023-07-01: Added symptom and inbuilt FAN switch step, formatted
2024-01-18: Added a Workaround power cycle, At times QFX5K will report a false alarm due to communication issues between Chassism and kernel.