Restore and Recovery

This section helps you to develop an approach to restore and recover of your Oracle database in the event of failure.

The following graphic shows an overview of the restore and recovery process:

It is possible to use BRRECOVER and BRRESTORE for homogeneous database copies. For more information, see Enhanced Support for Homogeneous Database Copies in SAP Note 1003028 .

You use the following tools for database restore and recovery:

Before you start to restore and recover your database, try to locate:

• The backups of the missing or faulty data files, or the required offline redo log files made with BRBACKUP or BRARCHIVE.

• The BRBACKUP logs and BRARCHIVE logs, which are important for the restore because they contain all the information about the backups, such as directories, volumes, and timestamps. BRRECOVER uses the logs to find the backups of the data files and the offline redo log files.

  Caution

  If you lose the entire database system, including such items as the BRBACKUP and BRARCHIVE logs and profiles, you need to perform Disaster Recovery.

  Note

  BRRECOVER recovery is not based on BRBACKUP or BRARCHIVE logs in database tables, because these tables are not available when you recover the database.

  You might also need to meet other prerequisites, depending on the context of the recovery.

• Restore

  BRRESTORE restores data files that have been damaged or are missing, using backups of the database files.

• Recovery

  BRRECOVER recovers transactions lost since the database backup, using backups of the offline redo log files to roll forward the lost transactions.

  BRRECOVER supports database recovery after:

  • Media errors, such as a disk crash or accidental deletion of database files

  • User errors such as software problems or when a user accidentally drops a table

  • Disaster, when the entire database is lost, including backup profiles and logs

  After recovery, BRRECOVER automatically rebuilds NOLOGGING indexes that were created during or after the backups used. For more information, see SAP Note 849485 .

You can perform restore, and recovery tasks from either of the following:

• The menus in BRTOOLS or BRGUI

  BRTOOLS or BRGUI calls the tools BRBACKUP, BRARCHIVE, BRRESTORE, or BRRECOVER as necessary to complete the task you have chosen.

• The command line

  In this way, you can use the tools BRBACKUP, BRARCHIVE, BRRESTORE, or BRRECOVER, but this requires expert knowledge.

  Recommendation

  We recommend you to use the DBA Planning Calendar for routine backup because this enables you to automatically schedule the backup.

  We recommend you to use the BRTOOLS or BRGUI menus for restore and recovery because BRTOOLS or BRGUI guides you through the necessary steps.

Proceed as follows to restore and recover your database:

1. To analyze the problem, check the:

   • Database alert log

   • Trace files belonging to the background processes in the directory $SAPDATA_HOME/saptrace/background or $SAPDATA_HOME/saptrace/diag.

   For more information, see Error Analysis.

2. Ask yourself the following questions:

   • What is the status of the database? Is it available or not?

   • What kind of error has occurred? A media or a user error?

   • Which files are corrupt?

   • What type of file is affected? Data files, control files, online redo log files?

   • If a media error has occurred, is software or hardware mirroring available?

   • Do you have a standby database?

3. If a user error has occurred, the database is still available, and you have enough time, perform a complete, offline backup before starting to restore and recover the database.

4. If a media error has occurred, you must replace the affected equipment and recreate the file system as it existed before the error.

5. Decide what kind of restore and recovery you want to perform:

   Scenario	Aim	Solution
   Media error such as a disk crash	You want to recover to the time of failure	Complete Database Recovery
   User or software error	You want to recover to a selected point in time	Database Point-In-Time Recovery
   User or software error within one component of a multicomponent database	You want to recover the affected component to a selected point in time.	Tablespace Point-in-Time Recovery
   Either of the following applies: Error in which all copies of redo log files are lost, but the database file backup is available You performed a complete or incremental offline or consistent online backup immediately before the error, such as during a software upgrade.	You want to reset the database to the state it was in at the most recent offline or consistent online backup.	Whole Database Reset
   Loss of entire database system, including backup profiles and logs	You want to recover as much as possible	Disaster Recovery