This post is part of a blog series.
Technically, this is a 21c feature, but it’s worth calling out some of those 21c improvements, because most customers are still running on 19c or earlier. That means when you upgrade to 26ai, you’ll pick up all the 21c goodies too!
Here’s one: Fast-Start Failover observer’s priority. In 19c, you could list preferred observers for each possible primary with the property PreferredObserverHosts , but you couldn’t actually assign an observer priority based, for example, to the observer’s location.
21c fixes that. Now, you can give each observer a priority by adding a colon and a number right after the hostname. The lower the number, the higher the priority. This lets you spell out exactly which observers should be chosen first if a promotion is needed.
The diagram below shows an example: the external site’s observer is set as the top pick for both databases at the primary and the secondary sites, with each site’s local observer as the backup (which is our recommendation in this case).
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1 2 3 |
edit database db_site1 set property PreferredObserverHosts='obs_ext:1,obs_site1:2'; edit database db_site2 set property PreferredObserverHosts='obs_ext:1,obs_site2:2'; |
You can create that setup now—thanks to observer priorities.
Latest posts by Ludovico (see all)
- Data Guard 26ai – #5: Fast-Start Failover Observer Priority - February 2, 2026
- Data Guard 26ai – #4: Faster DML Redirection - January 30, 2026
- Data Guard 26ai – #3: Choice of Lag Type for Fast-Start Failover - January 29, 2026