Redo I/O Is Higher On Active Data Guard Physical Standby Than Primary
(Doc ID 2249431.1)
Last updated on APRIL 03, 2020
Applies to:Oracle Database - Enterprise Edition - Version 126.96.36.199 and later
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Cloud Machine - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Oracle Database Backup Service - Version N/A and later
Information in this document applies to any platform.
The physical standby becomes un-synchronized with the primary and 'apply lag' may be found to grow via v$dataguard_stats and/or v$standby_event_histogram views.
When database performance metrics are captured for the physical standby it may appear that 'db file parallel read' waits or related datafile read I/O waits appear to spike heavily.
The redo being applied at the time is related to Automatic Optimizer Statistics against three very large partitioned tables.
Initialization parameter DB_LOST_WRITE_PROTECT has been set on both primary and physical standby databases.
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