The video explains best practices and different failure scenarios for different observer placements. It also shows how to configure high availability for the observer.
Here’s the summary:
- Always try to put the observer(s) on an external site.
- If you don’t have any, put it where the primary database is, and have one ready on the secondary site after the role transition.
- Don’t put the observer together with the standby database!
- Configure multiple observers for high availability, and use the PreferredObserverHosts Data Guard member property to ensure you never run the observer where the standby database is.