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This section tells you about resetting your Oracle database after a failure. You normally need to do this if either of the following applies:

  • An error occurred in which all copies of the redo log files are lost, but the database file backup is available.

  • You performed a complete offline backup or a consistent online backup immediately before the error, such as during a software upgrade.

With this function you can reset the database to a previous consistent state, at the time of either a complete offline or a consistent online backup. If you reset from an online backup, the consistent end point of the backup is used.

This section discusses how to approach whole database reset.

For more information about how to perform a whole database reset, see Whole Database Reset with BR*Tools.

You can now also use whole database reset for a standby database.

Prerequisites

  • We recommend you to perform a full offline backup. If the database is running, use SAP tools, otherwise use operating system tools.

  • You have the following data available if restore points are not used:

    • The BRBACKUP logs

    • The data file backups and, if selected, an incremental backup

    • If restoring from a consistent online backup, the accompanying redo log files that were saved in the same BRBACKUP run

Any types of database files - data, online redo log, control - might be unavailable on disk.

Features

The following graphic shows how a whole database reset works:

This graphic is explained in the accompanying text.

Activities

  1. Select Database Backup phase

    BRRECOVER determines the eligible backups using the entries in the summary log file for BRBACKUP, back<DBSID>.log (return code 0 or 1). The associated detail logs show whether the required data files were in the backup. The selected backup must be a complete offline or a consistent online backup. To minimize the subsequent recovery time, BRRECOVER always suggests the most recent backup.

    You can also select an offline or consistent online incremental backup to be restored. In this case, BRRECOVER automatically selects the corresponding full backup to restore all data files.

    You can also select a restore point if defined and still usable.

  2. Check Status of Database Files phase

    BRRECOVER checks the status of database files to determine which files are to be overwritten.

  3. Restore Control Files and Offline Redo Log Files phase

    BRRECOVER calls BRRESTORE to restore control files. At the same time, offline redo log files are restored if a consistent online backup was selected.

  4. Restore Data Files phase

    BRRECOVER calls BRRESTORE to restore all the data files to their original location.

  5. Apply Incremental Backup phase

    If you selected an incremental backup during the Select Database Backups phase, BRRECOVER calls BRRESTORE to restore and apply the selected incremental backup.

  6. Apply Offline Redo Log Files phase

    If a consistent online backup was selected, BRRECOVER calls SQLPLUS to apply the restored offline redo log files to the database.

  7. Restore Offline Redo Log Files and Flashback phase

    When restore points are defined, you can use flashback for the database reset. It is always possible to use a guaranteed restore point. However, it is only possible to use a normal restore when the time stamp or system change number (SCN) is contained in the flashback data.

    In this case, BRRECOVER calls BRRESTORE to restore offline redo log files needed for the flashback to the saparch or oraarch directory (if required), then resets the database to the chosen restore point using flashback.

    Caution Caution

    Before you use database flashback and restore points in your production environment, make sure you have tested it thoroughly.

    Database flashback does not replace regular backups.

    End of the caution.

    For more information, see Managing Flashback Database with BR*Tools.

  8. Open Database phase

    During this phase BRRECOVER:

    1. Opens the database

    2. Creates missing temporary files

    3. Checks the status of database files and tablespaces

    4. Deletes unnecessary files that are no longer used by the database