I've been scouring for a way to do this. We're constantly getting diskUsgThreshExcd traps sent to my SNMP monitoring system. We have separate monitoring for this outside of Storage Manager so I would like to disable them.
Here's where it's interesting. The Default OS Policy does not include the Rule for this Threshold Alert, and I can't find anywhere else it's defined except in the Rules pane. There are no custom rules configured at this time, so I know it's not buried in one of those.
Is there a way to disable the default rule/delete it completely?