Standby Database: BRARCHIVE Backup of Offline Redo Log Files

Use

You can use BRARCHIVE with the Oracle Standby Database to back up the offline redo log files.

BRARCHIVE can back up offline redo log files from the primary to the standby instance. This is possible because BRARCHIVE is able to copy offline redo log files to a local or remote hard disk.

Features

The following graphic illustrates how BRARCHIVE works with the standby database:

·        BRARCHIVE process on the primary host

This process copies the offline redo log files to an NFS-mounted or remote directory, which represents the archive directory (usually oraarch) on the standby host. For a mounted directory, the copy process uses an insecure network protocol. In this case, you should use BRARCHIVE with the -w|-verify option.

·        Reliable copy programs

BRARCHIVE can use reliable copy programs such as rcp, ftp, or scp for the copying of the offline redo log files from the primary host onto the standby host, with the backup_dev_type parameter set to stage. Therefore, NFS-mounting and verification are no longer necessary.

·        BRARCHIVE process on the standby host

This process waits for the offline redo log files to be copied into the local archive directory. If a redo log file was copied completely, BRARCHIVE applies these redo entries to the standby instance with the -m|- modify option, backing up the redo log file and deleting it if necessary. Therefore, BRARCHIVE starts the recovery process of the standby database, in which the offline redo log files are processed individually.

·        Delaying import of redo entries

You can delay importing the redo entries, using the <delay> parameter with the -m|- modify option. If a logical error occurs in the primary instance (for example, accidental deletion of a table), you can prevent this error from being imported in the standby instance, by stopping the BRARCHIVE run.

·        Importing offline redo log files

You import the offline redo log files with the following Oracle command:

RECOVER STANDBY DATABASE;

When the volume of offline redo log files is high, the import to the standby database is performed in parallel to the backup, leading to significantly faster processing. For more information, see -m|-modify.

To import the redo log files, the database user (usually SYSTEM) must have SYSDBA authorization.

BRARCHIVE can now automatically process new database files when importing offline redo log files into the standby database. In the past this caused an error.

However, if you access the database file with a softlink (for example, a raw device file), you must still set up the softlink manually on the standby database. You must do this at the same time as you set up the file on the primary database.