Performing Disaster Recovery

If you are in a disaster recovery scenario, then presumably you have lost the target database, the recovery catalog database, all control files, all online redo logs, and all parameter files.
To perform a disaster recovery, the minimum required set of backups is backups of some datafiles, some archived redo logs generated after the time of the backup, and at least one autobackup of the control file.
See Also:
"Control File and Server Parameter File Autobackups"
The basic procedure for disaster recovery is found in "Performing Recovery with a Backup Control File", with an additional first step of restoring an autobackup of the server parameter file as described in Oracle Database Backup and Recovery Basics. After the instance is started, you can restore an autobackup of the control file, mount it, then restore and recover the datafiles. Because you are restoring to a new host, you should review the considerations described in "Restoring the Database to a New Host".
The following scenario restores and recovers the database to the most recently available archived log, which in this example is log 1124 in thread 1. It assumes that:
You are restoring the database to a new host with the same directory structure.
You have one tape drive containing backups of all the datafiles and archived redo logs through log 1124, as well as autobackups of the control file and server parameter file.
You do not use a recovery catalog.
In this scenario, perform the following steps:
If possible, restore all relevant network files such as tnsnames.ora and listener.ora by means of operating system utilities.
Start RMAN and connect to the target database. If you do not have the Oracle Net files, then connect through operating system authentication.
Specify the DBID for the target database with the SET DBID command, as described in "Performing Recovery with a Backup Control File and No Recovery Catalog".
Run the STARTUP NOMOUNT command. RMAN attempts to start the instance with a dummy server parameter file.
Allocate a channel to the media manager and then run the RESTORE SPFILE FROM AUTOBACKUP command.
Run STARTUP FORCE NOMOUNT mode so that the instance is restarted with the restored server parameter file.
Allocate a channel to the media manager and then restore a control file autobackup (refer to"Performing Recovery with a Backup Control File and No Recovery Catalog").
Mount the restored control file.
Catalog any backups not recorded in the repository with the CATALOG command (refer to"Removing Recovery Catalog Records with Status DELETED").
Restore the datafiles to their original locations. If volume names have changed, then run SET NEWNAME commands before the restore and perform a switch after the restore to update the control file with the new locations for the datafiles (refer to"Performing Disaster Recovery").
Recover the datafiles. RMAN stops recovery when it reaches the log sequence number specified.
Open the database in RESETLOGS mode. Only complete this last step if you are certain that no other archived logs can be applied. # Start RMAN and connect to the target database
% rman TARGET SYS/oracle@trgt

# Set the DBID for the target database
RMAN> SET DBID 676549873;
RMAN> STARTUP FORCE NOMOUNT; # rman starts instance with dummy parameter file
RUN
{
ALLOCATE CHANNEL t1 DEVICE TYPE sbt;
RESTORE SPFILE FROM AUTOBACKUP;
}
# Restart instance with restored server parameter file
RMAN> STARTUP FORCE NOMOUNT;

RMAN> RUN
{
# Manually allocate a channel to the media manager
ALLOCATE CHANNEL t1 DEVICE TYPE sbt;
# Restore autobackup of the control file. This example assumes that you have
# accepted the default format for the autobackup name.
RESTORE CONTROLFILE FROM AUTOBACKUP;
# The set until command is used in case the database
# structure has changed in the most recent backups, and you wish to
# recover to that point-in-time. In this way RMAN restores the database
# to the same structure that the database had at the specified time.
ALTER DATABASE MOUNT;
SET UNTIL SEQUENCE 1124 THREAD 1;
RESTORE DATABASE;
RECOVER DATABASE;
}
RMAN> ALTER DATABASE OPEN RESETLOGS; # Reset the online logs after recovery
completes


The following example of the RUN command shows the same scenario except with new filenames for the restored datafiles:RMAN> RUN
{
# If you need to restore the files to new locations, tell Recovery Manager
# to do this using SET NEWNAME commands:
SET NEWNAME FOR DATAFILE 1 TO '/dev/vgd_1_0/rlvt5_500M_1';
SET NEWNAME FOR DATAFILE 2 TO '/dev/vgd_1_0/rlvt5_500M_2';
SET NEWNAME FOR DATAFILE 3 TO '/dev/vgd_1_0/rlvt5_500M_3';
ALLOCATE CHANNEL t1 DEVICE TYPE sbt;
RESTORE CONTROLFILE FROM AUTOBACKUP;
ALTER DATABASE MOUNT;
SET UNTIL SEQUENCE 124 THREAD 1;
RESTORE DATABASE;
SWITCH DATAFILE ALL; # Update control file with new location of datafiles.
RECOVER DATABASE;
}
RMAN> ALTER DATABASE OPEN RESETLOGS;