Recovering Image Copies

Recover Image Copies by using Incremental Backup

RMAN Can Recover Image Copies by using Incremental Backups.

With this Recovery method, you use RMAN to recover a copy of data file- that is, you roll forward(recover) the image copy to the specified point in time by applying the incremental backups to the image copy.

The Image copy is updated with all changes up through the SCN at which incremental backup was taken.

Then, RMAN uses the resulting updated data file in media recovery just as it would use a full image copy taken at the SCN, without the overhead of performing a full image copy of the database everyday.

Benefits

You reduce the time required for media recovery (using archive logs) because you need to apply archive logs only since the last incremental backup.

You do not need to perform a full image copy after the incremental restoration.

Example:

RMAN > recover copy of database with tag ‘daily_inc’;

RMAN> backup incremental level 1 for recover of copy with tag ‘daily_inc’ database;

Performing a Fast Switch to Image Copies

Steps

 1.   Take data file offline.

 2.   Use the Switch to Copy Command to switch to image copy.

 3.   Recover Data Files.

 4.   Bring the Data files online.

Do the Following to put the files back into their Original Location

 1.   Create the image copy of the data file in the original location.

 2.   Take data files offline.

 3.   Switch to Copy

 4.   Recover Data Files.

 5.   Bring the data files online.

Use the SET NEWNAME Command in a RUN Block to restore to a non-default location.

RUN

{

          Allocate channel c1 device type disk;

          Allocate channel c2 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’;

}

Here when the restore command executes, the users01.dbf data file is restored to /disk2/user01.dbf. it is written there, but the control file is still not pointing to that location. The Switch command cause the control file to be updated with the new location.

Order of Precedence for the SET NEWNAME command as follows

SET NEWNAME FOR DATAFILE or SET NEWNAME FOR TEMPFILE

SET NEWNAME FOR TABLESPACE

SET NEWNAME FOR DATABASE