Thursday , September 28 2023

Backup And Recovery In Data Guard Configuration

Physical Standby Databases Since Primary and block by block are the same, backups of datafile, control file and archive redo logs taken from Standby database can be used in Primary database.

However, it is necessary to use Recovery Catalog for such use.

On the other hand, SPFILE backups cannot be used between each other as there may be parameter changes. There are some rules for a backup like this.

Backup must be taken from the physical database,

You must be connected to the recovery catalog while taking a backup,

The physical standby database must be connected with TARGET.

Normally all database files and backup files are associated with DB_UNIQUE_NAME.

However, it is associated with a different database with the CHANGE … RESET DB_UNIQUE_NAME command.

However, this does not mean that a backup taken cannot be used in other databases.

Attribution can only be thought of as ownership.

The owner of that backup or database file can be thought of as the database from which it was taken.

Disk backups can only be accessed by the database it is associated with, while tape backups can be accessed by all databases.

However, with the CATALOG command, the image copy backup file is also associated with other databases.

Since Logical Standby Databases are not the same block by block, the backups taken cannot be used in the Primary database.

Likewise, a backup taken from the Primary database cannot be used in the Logical Standby database. Because,

In case of a problem in the Datafile or online redo log files, the backups taken from the Logical Standby database should be used.

If the entire Logical Standby Database is lost, the database must be rebuilt.

If we lose all copies of the control file, we need to create a binary copy of the control file in order to perform the Recovery.

This copy cannot be created with the Trace File or CREATE CONTROLFILE command. But it is created as follows.

Logical Standby Database is closed and the control file is copied to a backup.

Or when the database is open, ALTER DATABASE BACKUP TO CONTROL FILE TO ‘<filename>’;

According to Oracle, Maximum Availability Architecture (MAA),

Taking daily incremental backups of both Primary and Standby databases in Data Guard Environment,

Setting the MTTR parameter,

Recommends using a separate server for Recovery Catalog.



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