Proactively ? What's your definition of proactive ? It implies you do things to prevent a cluster failover.
Make sure you maintain your NetApp. Keep it cool, provide clean power, the list could go on.
Enabling autosupport to notify you of health events, watching out for BURTS regarding your equipment,
using SNMP traps and monitoring are all good proactive practices.
But an autosupport message to notify you of a cluster failover is the primary way to know that it happened.
I hope this response has been helpful to you.
At your service,
Eugene E. Kashpureff
Senior Systems Architect / NetApp Certified Instructor
(P.S. I appreciate points for helpful or correct answers.)