Oracle "DBO - DG Applied Gap" Alarm – Behavior When Standby Database Is Down (4380527)

The "DBO - DG Applied Gap" alarm checks if there is a delay (called a gap) between the primary Oracle database and its standby database. It looks at how many log files have been applied on the standby compared to the primary. This helps make sure that if the primary fails, the standby is ready to take over with minimal data loss.

If the standby database is down or unreachable, the alarm may not work as expected. The alarm uses Oracle system views to get information about the standby. If the standby is not reporting its status or log activity, the alarm may not trigger because it can't calculate the gap.

When the standby is down:

• The alarm may not trigger because the system can't see the standby destination.
• The query used by the alarm depends on data from views like gv$archive_dest, gv$archive_dest_status, and v$archived_log.
• If the standby is missing from these views, the alarm logic won't run properly.

To monitor this situation, it's important to also check if the standby destination is reporting errors or is missing entirely from the system views.