Restoring Datafiles to a Nondefault Location

Restoring Datafiles to a Nondefault Location

If you cannot restore datafiles to their default locations, then you must update the control file to reflect the new locations of the datafiles. Use the RMAN SET NEWNAMEcommand within a RUN command to specify the new filename. Afterward, use a SWITCH command, which is equivalent to using the SQL statement ALTER DATABASE RENAME FILE, to update the names of the datafiles in the control file. SWITCH DATAFILE ALL updates the control file to reflect the new names for all datafiles for which a SET NEWNAMEhas been issued in a RUN command.

SWITCH Purpose

Use the SWITCH command to perform either of the following operations:

·         Update the file names for a database, tablespace, or data file to the latest image copies available for the specified files

·         Update the file names for data files and temp files for which you have issued a SET NEWNAME command

A SWITCH is equivalent to the SQL statement ALTER DATABASE RENAME FILE: the names of the files in the RMAN repository are updated, but the database does not rename the files at the operating system level.

Prerequisites

RMAN must be connected to a target database. When switching tablespaces, data files, or temp files, the files must be offline. When switching the whole database, the database must not be open.

Usage Notes

The SWITCH command deletes the RMAN repository records for the data file copy from the recovery catalog and updates the control file records to statusDELETED.

If RMAN is connected to a recovery catalog, and if the database is using a control file restored from backup, then SWITCH updates the control file with records of any data files known to the recovery catalog but missing from the control file.

Execute SWITCH ... TO COPY only at the RMAN prompt. Use SWITCH without TO COPY only within a RUN block.

Examples

Example Switching to Image Copies to Avoid Restoring from Backup

Assume that a disk fails, rendering all data files in the users tablespace inaccessible. Image copies of all data files in this tablespace exist in the fast recovery area. After starting RMAN and connecting to the database as TARGET, you can run SWITCH to point the control file to the new data files and then run RECOVER as follows:

SQL "ALTER TABLESPACE users OFFLINE IMMEDIATE";

SWITCH TABLESPACE users TO COPY;

RECOVER TABLESPACE users;

SQL "ALTER TABLESPACE users ONLINE";

Example Switching Data File File Names After a Restore to a New Location

Assume that a disk fails, forcing you to restore a data file to a new disk location. After starting RMAN and connecting to the database as TARGET, you can use the SET NEWNAME command to rename the data file, then RESTORE to restore the missing data file. You run SWITCH to point the control file to the new data file and then RECOVER. This example allocates both disk and tape channels.

RUN

{

  ALLOCATE CHANNEL dev1 DEVICE TYPE DISK;

  ALLOCATE CHANNEL dev2 DEVICE TYPE sbt;

  SQL "ALTER TABLESPACE users OFFLINE IMMEDIATE";

  SET NEWNAME FOR DATAFILE '/disk1/oradata/prod/users01.dbf'

                        TO '/disk2/users01.dbf';

  RESTORE TABLESPACE users;

  SWITCH DATAFILE ALL;

  RECOVER TABLESPACE users;

  SQL "ALTER TABLESPACE users ONLINE";

}

Example Renaming Temp Files Using SET NEWNAME and SWITCH TEMPFILE ALL

This example demonstrates using SET NEWNAME to specify new names for several temp files, and SWITCH TEMPFILE ALL to rename the temp files to the specified names. The database must be closed at the beginning of this procedure. The temp files are re-created at the new locations when the database is opened.

CONNECT TARGET /

STARTUP FORCE MOUNT

RUN

{ 

  SET NEWNAME FOR TEMPFILE 1 TO '/disk2/temp01.dbf';

  SET NEWNAME FOR TEMPFILE 2 TO '/disk2/temp02.dbf';

  SET NEWNAME FOR TEMPFILE 3 TO '/disk2/temp03.dbf';

  SWITCH TEMPFILE ALL; 

  RESTORE DATABASE; 

  RECOVER DATABASE; 

  ALTER DATABASE OPEN;

}

Example Switching to a Data File Copy

The following command switches the data file in the tools tablespace to the data file copy

named /disk2/tools.copy:

RUN

{

  SQL "ALTER TABLESPACE tools OFFLINE IMMEDIATE";

  SWITCH DATAFILE '/disk1/oradata/prod/tools01.dbf'

  TO DATAFILECOPY '/disk2/tools.copy';

  RECOVER TABLESPACE tools;

  SQL "ALTER TABLESPACE tools ONLINE";

}

About Complete Database Recovery

You use the RESTORE and RECOVER commands to restore and recover the database. During the recovery, RMAN automatically restores backups of any needed archived redo logs. If backups are stored on a media manager, then channels must be configured in advance or a RUN block with ALLOCATE CHANNEL commands must be used to enable access to backups stored there.

If RMAN restores archived redo logs to the fast recovery area during a recovery, then it automatically deletes the restored logs after applying them to the datafiles. Otherwise, you can use the DELETE ARCHIVELOG command to delete restored archived redo logs from disk when they are no longer needed for recovery. For example, you can enter the following command:

RECOVER DATABASE DELETE ARCHIVELOG;