We have two 6520 switches. Both switches are in the same rack, and a couple of days ago we had to move one of the power connections for each switch to a different PDU - i.e for a few seconds each switch lost one PSU whilst the power cord was moved to a different socket.
As expected the fan speed increased for the brief spell when power redundancy was reduced, and returned to normal when power was restored. However, the second switch has behaved differently and the fan speed remains high following the same process, and remains high several days later.
The switch monitors show that power and fan operations are good, even though the fan speed is excessively high.
Has anyone come across this type of behaviour, and how to reset the fans to normal operation...??
So far the only suggestions I have had are an OS reboot (hareboot), or a full switch power down. Both of which I would prefer to avoid if there is a less disruptive alternative.