Approach to Restore and Recovery (SAP Library - SAP Database Guide: Oracle (BC-DB-ORA-DBA))

Approach to Restore and Recovery

Purpose

SAPDBA supports the recovery of the database after:

Media errors, such as a disk crash or accidental deletion of a database file
User errors such as software problems or when a user accidentally drops a table

This section tells you how to work out the best approach to get your database up and running again.

Caution

Always analyze the problem carefully before attempting to recover your database. If in doubt, seek support from SAP. The business costs of an incorrect or delayed recovery can easily outweigh consultancy fees.

Recommendation

We strongly recommend you to practice restore and recovery on a test system as similar as possible to your production system. Repeat this regularly, especially after you have modified the production system.

The SAPDBA restore and recovery functions are based on the SAP tools BRBACKUP, BRARCHIVE, and BRRESTORE:

During a restore, BRRESTORE copies database files from the backup medium to disk
During a recovery, SAPDBA applies the data in the backups of the offline redo log files to the restored database files

Prerequisites

Try to locate:

The backups of the missing or faulty data files made with BRBACKUP or BRARCHIVE.

The BRBACKUP logs and BRARCHIVE logs, which are very important for the restore because they contain all the information about the backups, such as directories, volumes, and timestamps. SAPDBA 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

SAPDBA 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.

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

This graphic is explained in the accompanying text

Process Flow

To analyze the problem, check the:

Database alert log

Trace files belonging to the background processes in the directory $ORACLE_HOME/saptrace/background.

For more information, see Error Analysis.

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?

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.

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

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

Scenario	Aim	Solution
Loss of entire database system	You want to recover as much as possible	Disaster Recovery
Media error such as a disk crash	You want to recover to the time of failure	Partial restore and complete recovery with SAPDBA
User or software error	You want to recover to a selected point in time	Full restore and 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 full offline backup immediately before the error, such as during a software upgrade.	To reset the database to the state it was in at the most recent offline backup. No recovery is possible, because the redo log files are not available.	Database reset

Note

Only if you are very experienced, you might want to consider the following:

Restore of one tablespace

Restore of individual files