Impact of Very Large Controlfiles on Data Guard Environments
(Doc ID 753893.1)
Last updated on APRIL 03, 2020
Applies to:Oracle Database - Enterprise Edition - Version 10.2.0.1 and later
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Cloud Machine - Version N/A and later
Oracle Database Exadata Express Cloud Service - Version N/A and later
Oracle Database Backup Service - Version N/A and later
Information in this document applies to any platform.
One or more of the following behaviors may be encountered:
- One or more processes related to Data Guard activity may be seen waiting off and on or in wait for either 'control file sequential read' or 'enq: CF - contention'
- These processes may end up blocking LGWR or some other critical background processes on primary
- The waits may be seen on both primary and standby or just one site
- Ultimately the application accessing the primary may be impacted by stalling at times when waiting for COMMIT approval.
- These problems affect all transport modes and protection levels in any Data Guard configuration (e.g. MAXIUMUM PERFORMANCE with ASYNC).
- With 12.1 and up, this is less of an issue due to additional code optimizations (discussed in Solution section).
No particular change may trigger this issue beyond the fact that time and a large amount of archive log activity is or was occurring at some point between primary and standby.
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