This post is part of a blog series.
Just like observer priorities, this is another cool feature first introduced in Oracle 21c.
If your Fast-Start Failover setup doesn’t have a third site for the observer, the usual advice is to place it with your primary database. But if you want true high availability, making sure the observer is always up, you’ll want two observers on the primary site and two on the secondary site (for when the standby takes over as primary).
Before 21c, you could only use up to three observers, which made this setup impossible.
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edit database db_site1 set property PreferredObserverHosts='obs1_site1,obs2_site1'; edit database db_site2 set property PreferredObserverHosts='obs1_site2,obs2_site2'; |
Starting with 21c (and, of course, 26ai), you can now configure four observers. That solves the high-availability challenge when you’ve only got two sites.
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