Restoring an RMAN Backup to Another Node /Clone Database

In certain circumstances, it may be desirable to restore a database from an RMAN backup onto a machine other than the original host. 
For example,Restore and recover data at a given point in time for UAT/Testing, or to duplicate a production instance.
The example assumes:
the target database is on host A
the database is to be restored onto host B
the directory structure of host B is different to host A
the ORACLE_SID will not change for the restored database
a recovery catalog is being used
the backups were carried out to disk (for illustrative purposes, and to disassociate from any media manager specific issues)

The following steps are required:
1. backup the target on host A
2. list the datafile locations on host A
3. make the backup available to host B
4. make a copy of the init.ora available to host B
5. edit the init.ora to reflect directory structure changes
6. configure SQL*Net connectivity from host to the recovery catalog and duplicated database
7. set up a password file for the duplicated database
8. startup nomount the duplicated database
9. RMAN restore the controlfile(s)
10. mount the database
11. restore and rename the datafiles
12. recover and open the database
These steps are expanded further below.

1.Backup the Target on Host A
The target database needs to be backed up using RMAN. The following  commands of RMAN doing an online database backup. In this example, the backup sets are written to disk.

RMAN>
run {
allocate channel t1 type disk;
allocate channel t2 type disk;
allocate channel t3 type disk;
#backup the whole db
backup tag whole_database_open format '/oracle/backups/df_%u' database;
# switch out of the current logfile
sql 'alter system archive log current';
#backup the archived logs
backup archivelog all format '/oracle/backups/al_%u';
# backup a copy of the controlfile that contains records for the other backups just made
backup current controlfile tag = cf1 format '/oracle/backups/cf_%u';
}

2.List Datafile Locations on Host A
The datafile numbers and location on host A are required. These datafile locations will change on host B 
select file#, name from v$datafile;
file#   name
-----   -----------------------------------------------------------
1       /oracle/OFA_base/u01/oradata/TEST/system01.dbf
2       /oracle/OFA_base/u01/oradata/TEST/rbs01.dbf
3       /oracle/OFA_base/u01/oradata/TEST/temp01.dbf
4       /oracle/OFA_base/u01/oradata/TEST/tools01.dbf
5       /oracle/OFA_base/u01/oradata/TEST/users01.dbf
6       /oracle/OFA_base/u01/oradata/TEST/users02.dbf
7       /oracle/OFA_base/u01/oradata/TEST/rbs02.dbf
8       /oracle/OFA_base/u01/oradata/TEST/rcvcat.dbf

The log file names should also be recorded
select group#, member from v$logfile;
group#    member
---------   -----------------------------------------------------------
1            /oracle/OFA_base/u01/oradata/TEST/redo01.log
2            /oracle/OFA_base/u01/oradata/TEST/redo02.log
3            /oracle/OFA_base/u01/oradata/TEST/redo03.log

3 Make the Backups Available to Host B
3.1 Disk Backups
During restore, RMAN will expect the backup sets to be located in the same directory as written to during the backup. For disk backups, the DBA can accomplish this in many ways: set up an NFS directory, mounted on both host A and host B create the same directory structure on host A and host B, use of symbolic links on host B,FTP backup to host B.
If backup directory is not same at HOST B then catalog backup files using RMAN.
3.2 Tape Backups
The media management software must be configured such that host B is a media manager client, and can read the backup sets. The media management vendor should be consulted for support on this issue.

4. and 5. init.ora on host B
The "init.ora" needs to be made available on host B. Any location specific parameters must be ammended. For example,
*_dump_dest
log_archive_dest*
control_files

6. SQL*Net configuration
If running rman from host A:
a. connectivity to the catalog remains unchanged
b. configure tnsnames.ora on host A to connect to duplicated db on host B configure listener.ora on host B to accept connections for duplicated database
If running rman from host B:
a. configure tnsnames.ora on host B to connect to catalog listener.ora on catalog host remains unchanged
b. configure tnsnames.ora on host B to connect to duplicated db on host B configure listener.ora on host B to accept connections for duplicated database
If running rman from host C (ie, neither host A or host B):
a. connectivity to the catalog remains unchanged
b. configure tnsnames.ora on host C to connect to duplicated db on host B configure listener.ora on host B to accept connections for duplicated database

7. Setup Password File
In order to allow RMAN remote connections, a password file must be setup for the duplicated database. 
orapwd file=$ORACLE_HOME/dbs/orapw$ORACLE_SID password=password1

8. Startup nomount the database
SVRMGR> startup nomount pfile=<location of init.ora>

9. RMAN restore the controlfile(s)
Restore the controlfile(s). 
RMAN>
run{
allocate channel c1 type disk;
restore controlfile;
}

10. Mount the database
SVRMGR> alter database mount;

11. Rename and restore the datafiles
Rename and Restore the Files, and perform database recovery. RMAN can be used to change the location of the datafiles from the location on host A (see Section 2) to the new location on host B.
RMAN>
run {
allocate channel c1 type disk;
allocate channel c2 type disk;
allocate channel c3 type disk;
set newname for datafile 1 to '/oracle/datafiles/system01.dbf';
set newname for datafile 2 to '/oracle/datafiles/rbs01.dbf';
set newname for datafile 3 to '/oracle/datafiles/temp01.dbf';
set newname for datafile 4 to '/oracle/datafiles/tools01.dbf';
set newname for datafile 5 to '/oracle/datafiles/users01.dbf';
set newname for datafile 6 to '/oracle/datafiles/users02.dbf';
set newname for datafile 7 to '/oracle/datafiles/rbs02.dbf';
set newname for datafile 8 to '/oracle/datafiles/rcvcat.dbf';
restore database;
switch datafile all;
}


12. Recover and open the database
Perform incomplete recovery:
SVRMGR> recover database using backup controlfile until cancel;
Forward the database applying archived redo log files until you decide to stop recovery by typing cancel at the prompt (assuming that you have required archived redo log files in the log_archive_dest directory). You may archive the source database redo log files and apply them at the target database if required.
SVRMGR> alter database open resetlogs;
Note: this will create the online redo logs in the same location as that on host A. If this directory location does not exist, then this will fail with:
ora344 : unable to recreate online log <name>
The workaround is to rename the logfiles prior to opening the database:
SVRMGR> alter database rename file '<host A location>' to '<host B location>';
Alternatively, the logfile groups can be dropped and recreated.