Howto make a consistent RMAN backup in an Standby database in Active DataGuard mode
Last updated on MARCH 26, 2018
Applies to:Oracle Database - Enterprise Edition - Version 188.8.131.52 and later
Enterprise Manager for Oracle Database - Version 184.108.40.206.0 to 220.127.116.11.0 [Release 12.1]
Information in this document applies to any platform.
Howto create a consistent RMAN backup on a Standby database in Active Dataguard Mode.
Consistent means, that the backup is having the datafiles and the related archived redologs, so that it can be opened with this backup. This done on the Primary database by using :
This will execute the following :
- Backup the existing archived redologs
- Backup the datafiles
- Switch a logfile
- Backup all the archives again, but this time it will include all the archived redologs created during and just after the datafile backup. This are the archives which are required to make the datafile backup consistent.
The goal of this document it to accomplish this in an Active DataGuard database.
An Active DataGuard database is a standby database which is open in READ ONLY, but with an ongoing recovery.
This ongoing recovery is updating the datablocks, even while the database is in READ ONLY mode.
From an RMAN perspective the datafiles will behave the same as in a Primary database, meaning that they are FUZZY and will need some recovery to become consistent.
As the standby database is open in READ ONLY, RMAN will NOT be able to force a switch. This is only done when a database is in READ WRITE. The archives are only created when the Primary is switching a logfile. So the above step(4) will NOT backup any new archived redologs and therefor this total backup will not be consistent as it requires additional archives which are not backed up (yet).
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