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Title
Gap value of the Data Guard Received Gap metric looks wrong -
Description
A user received an alert from the Dataguard Received Gap metric.
Triggered at: 11/4/15 9:20 PM
DG Received Gap
The gap of logs received on destination /oracle/MYINSTANCE/flashback_recovery/oraarch2 is 114613 logs.The number reported in the alarm is wrong.
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Cause
The Data Guard gaps query only needs to be executed on the primary database and the associated alarm should then be fired on the primary database and not on the standby.The reason that we also execute it on the standby database is because some of our customers are using a cascaded data guard configuration so the standby database also sends redo to other (additional) standby database, therefore we also monitor the standby database in order to detect gap between the standby database to the cascaded standby.In this particular environment the logical standby database had two false standby archive destinations that caused false alarms. -
Resolution
Users can disable the alarm on the logical standby database (MYHOST-MYINSTANCE). The result will be that the alarm can be fired only on the primary database, so only in cases where there is a gap between the primary database to the logical database, we will fire an alarm. This will stop the false alarms on the logical database.