RMAN RESTORE

Restore Database from a full RMAN backup

Restoring a database to a new server from a full RMAN backup is a common requirement when migrating databases to new hardware or recovering from a disaster. This process involves copying the RMAN backups from the original server, restoring the control file, datafiles, and performing recovery on the new server. Below are the detailed steps to achieve this:

1. Prerequisites

Before starting the RMAN restore to a new server, ensure the following:

• You have a full RMAN backup of the original database, including datafiles, archived redo logs, control file, and server parameter file (SPFILE).

• The target server has Oracle software installed and configured.

• The new server has the necessary storage and directories for the Oracle database files.

2. Prepare the New Server

• Install the same version of Oracle Database as the source system on the new server.

• Configure Oracle on the new server with the same directory structure or adjust paths as needed (if directory structures differ, you will need to update paths during restoration).

• Set necessary environment variables like ORACLE_HOME, ORACLE_SID, and PATH.

3. Transfer Backup Files

Copy all RMAN backup files from the source server to the new server. These backup files should include:

• Datafile backups

• Archived redo log backups

• Control file autobackups

• SPFILE backups

Make sure the directory structure on the new server is consistent or update the paths in the restore process if needed.

4. Restore and Recover Database on New Server

Once the backup files are copied to the new server, follow these steps to restore and recover the database:

a. Start RMAN and Connect to the Target Database

On the new server, start RMAN.
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$ rman target /

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2. Set the DBID (Database Identifier) of the original database:

   • You can find the DBID in the RMAN backup log, RMAN backup pieces, or from the original database.

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RMAN> SET DBID <dbid_value>;

b. Restore the Control File

1. Start the instance in nomount mode:

   • The control file is required to mount the database, but it hasn’t been restored yet.

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RMAN> STARTUP NOMOUNT;

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3. Restore the control file from the backup:

   • Assuming the control file autobackup is available, use the following command to restore it:

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RMAN> RESTORE CONTROLFILE FROM AUTOBACKUP;

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   • Alternatively, if you know the exact backup piece containing the control file:

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RMAN> RESTORE CONTROLFILE FROM '/path/to/controlfile/backup';

Mount the database:
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RMAN> ALTER DATABASE MOUNT;

c. Catalog the Backup Files

If the backup files are in a different location on the new server, catalog them to let RMAN know where they are:

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RMAN> CATALOG START WITH '/new/path/to/backup/files/';

d. Restore the SPFILE (if needed)

If the SPFILE was backed up and you need to restore it:

Shutdown the instance:
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RMAN> SHUTDOWN IMMEDIATE;

Restore the SPFILE:
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RMAN> RESTORE SPFILE FROM AUTOBACKUP;

Restart the instance with the restored SPFILE:
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RMAN> STARTUP FORCE NOMOUNT;

e. Restore the Database

Restore the datafiles from the backup:
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RMAN> RESTORE DATABASE;

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2. RMAN will automatically restore the datafiles from the backups that were cataloged or are in the default location.

f. Recover the Database

After restoring the datafiles, perform media recovery to apply all necessary archived redo logs:
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RMAN> RECOVER DATABASE;

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2. RMAN will apply the necessary archived redo logs to bring the database to a consistent state.

g. Open the Database

Once recovery is complete, you can open the database. Since the database is restored to a new server, you must open it with the RESETLOGS option:
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RMAN> ALTER DATABASE OPEN RESETLOGS;

5. Modify File Locations (if needed)

If the file paths on the new server differ from the original server (for example, if the file system layout is different), you can use RMAN’s SET NEWNAME command to modify the locations of datafiles, online redo logs, and control files during the restore process.

Example of Using SET NEWNAME

Before restoring the database, use SET NEWNAME to redirect the datafiles:
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RUN {

  SET NEWNAME FOR DATAFILE 1 TO '/newpath/system01.dbf';

  SET NEWNAME FOR DATAFILE 2 TO '/newpath/sysaux01.dbf';

  SET NEWNAME FOR DATAFILE 3 TO '/newpath/undotbs01.dbf';

  SET NEWNAME FOR DATAFILE 4 TO '/newpath/users01.dbf';

  RESTORE DATABASE;

  SWITCH DATAFILE ALL;

  RECOVER DATABASE;

}

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2. This method ensures that RMAN restores the files to the new directory paths.

6. Update Database Configuration (Optional)

After restoring the database to the new server, you may need to perform additional tasks, such as:

• Updating listener configuration (listener.ora).

• Changing TNS configuration (tnsnames.ora).

• Adjusting any environment-specific configurations (e.g., database directories, logs).

7. Post-Restoration Verification

Verify that the database is functioning correctly:
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SQL> SELECT status FROM v$instance;

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2. Check the alert log and RMAN log files for any errors during the restore process.

Example: RMAN Restore on New Server

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-- Step 1: Set the DBID

RMAN> SET DBID 123456789;

-- Step 2: Startup the database in NOMOUNT mode

RMAN> STARTUP NOMOUNT;

-- Step 3: Restore the control file from autobackup

RMAN> RESTORE CONTROLFILE FROM AUTOBACKUP;

-- Step 4: Mount the database

RMAN> ALTER DATABASE MOUNT;

-- Step 5: Catalog backup pieces (if needed)

RMAN> CATALOG START WITH '/new/server/backup/';

-- Step 6: Restore the SPFILE (if required)

RMAN> RESTORE SPFILE FROM AUTOBACKUP;

-- Step 7: Restore the database

RMAN> RESTORE DATABASE;

-- Step 8: Recover the database

RMAN> RECOVER DATABASE;

-- Step 9: Open the database with RESETLOGS

RMAN> ALTER DATABASE OPEN RESETLOGS;

Key Considerations

• Same Oracle Version: Ensure the new server has the same version of Oracle installed as on the source server.

• Network Configuration: If you need remote access to the new database, ensure the listener is configured properly.

• Password File: Copy the password file from the original server if using remote authentication for sysdba.

This method outlines the process for restoring a full RMAN backup to a new server, allowing for a smooth database migration or disaster recovery process.