Below is the procedure with an example of using RMAN to copy a database to another directory:

1. Connect to the target database using rman and backup the database ---> NODE 1
   
   $ rman target /Recovery Manager: Release 10.2.0.1.0 - Production on Tue Feb 13 00:29:33
   2007Copyright ? 1982, 2005, Oracle. All rights reserved.connected to target database: ORA10G (DBID=3932056136)RMAN>
   backup database plus archivelog;Starting backup at 13-FEB-07current log archivedusing channel ORA_DISK_1channel
   ORA_DISK_1: starting archive log backupsetchannel ORA_DISK_1: specifying archive log(s) in backup setinput archive log thread=1
   sequence=143 recid=109 stamp=614392105channel ORA_DISK_1: starting piece 1 at 13-FEB-07channel ORA_DISK_1: finished piece
   1 at 13-FEB-07piece handle=/u01/oracle/product/oradata/ora10g/fra/ORA10G/backupset/2007_02_13/o1_mf_annnn_TAG20070213T002825_2x21kbds_.bkp
   tag=TAG20070213T002825 comment=NONEchannel ORA_DISK_1: backup set complete, elapsed time: 00:00:02Finished backup at 13-FEB-07Starting
   backup at 13-FEB-07using channel ORA_DISK_1channel ORA_DISK_1: starting full datafile backupsetchannel ORA_DISK_1: specifying
   datafile(s) in backupsetinput datafile fno=00003 name=/u01/oracle/product/oradata/ora10g/data/sysaux01.dbfinput datafile
   fno=00001 name=/u01/oracle/product/oradata/ora10g/data/system01.dbfinput datafile fno=00002 name=/u01/oracle/product/oradata/ora10g/data/undotbs01.dbfinput
   datafile fno=00004 name=/u01/oracle/product/oradata/ora10g/data/users01.dbfinput datafile fno=00005 name=/home/oracle/1.dbfinput
   datafile fno=00006 name=/u01/oracle/product/oradata/ora10g/data/sysaux02.dbfinput datafile fno=00007 name=/u01/oracle/product/oradata/ora10g/data/undotbs02.dbfchannel
   ORA_DISK_1: starting piece 1 at 13-FEB-07channel ORA_DISK_1: finished piece 1 at 13-FEB-07piece handle=/u01/oracle/product/oradata/ora10g/fra/ORA10G/backupset/2007_02_13/o1_mf_nnndf_TAG20070213T002827_2x21kd12_.bkp
   tag=TAG20070213T002827 comment=NONEchannel ORA_DISK_1: backup set complete, elapsed time: 00:00:55Finished backup at 13-FEB-07Starting
   backup at 13-FEB-07current log archivedusing channel ORA_DISK_1channel ORA_DISK_1: starting archive log backupsetchannel
   ORA_DISK_1: specifying archive log(s) in backup setinput archive log thread=1 sequence=144 recid=110 stamp=614392165channel
   ORA_DISK_1: starting piece 1 at 13-FEB-07channel ORA_DISK_1: finished piece 1 at 13-FEB-07piece handle=/u01/oracle/product/oradata/ora10g/fra/ORA10G/backupset/2007_02_13/o1_mf_annnn_TAG20070213T002925_2x21m6ty_.bkp
   tag=TAG20070213T002925 comment=NONEchannel ORA_DISK_1: backup set complete, elapsed time: 00:00:02Finished backup at 13-FEB-07Starting
   Control File and SPFILE Autobackup at 13-FEB-07piece handle=/u01/oracle/product/ora10g/dbs/c-3932056136-20070213-02 comment=NONEFinished Control File and SPFILE Autobackup at 13-FEB-07RMAN> exit
   

2. Move the following files to the NODE 2 :
   
   + The database backup pieces
   + Controlfile backup piece
   + The parameter file i.e init.ora file

3. Edit the PFILE on NODE 2 to change the environment specific parameters like .
   
   user_dump_dest =
   background_dump_dest =
   control_files =

4. Once the PFILE is suitably modified invoke Rman on the NODE 2 after setting the Oracle environment variables and start the database in nomount mode:
   
   [oracle@test-br test]$ export ORACLE_HOME=/u01/oracle/product/ora10g
   [oracle@test-br test]$ export ORACLE_SID=ora10g
   [oracle@test-br test]$ export PATH=$ORACLE_HOME/bin:$PATH
   [oracle@test-br test]$ rman target /
   Recovery Manager: Release 10.2.0.1.0 - Production on Tue Feb 13 00:36:55 2007
   Copyright ? 1982, 2005, Oracle. All rights reserved.
   connected to target database (not started)
   RMAN> startup nomount
   Oracle instance started
   Total System Global Area 205520896 bytes
   Fixed Size 1218508 bytes
   Variable Size 75499572 bytes
   Database Buffers 121634816 bytes
   Redo Buffers 7168000 bytes

5. Restore the controlfile from the backup piece.
   
   RMAN> restore controlfile from '/u01/oracle/product/ora10g/dbs/c-3932056136-20070213-02';
   Starting restore at 13-FEB-07
   using target database control file instead of recovery catalog
   allocated channel: ORA_DISK_1
   channel ORA_DISK_1: sid=155 devtype=DISK
   channel ORA_DISK_1: restoring control file
   channel ORA_DISK_1: restore complete,
   elapsed time: 00:00:02
   output filename=/u01/oracle/product/oradata/ora10g/cntrl/control01.ctl
   Finished restore at 13-FEB-07

6. Mount the database.
   
   RMAN> alter database mount ;

7. Now catalog the backup pieces that were shipped from NODE 1.
   
   RMAN> catalog backuppiece '/home/oracle/test/backup/o1_mf_annnn_TAG20070213T002925_2x21m6ty_.bkp';Starting
   implicit crosscheck backup at 13-FEB-07allocated channel: ORA_DISK_1channel ORA_DISK_1: sid=155 devtype=DISKCrosschecked
   3 objectsFinished implicit crosscheck backup at 13-FEB-07Starting implicit crosscheck copy at 13-FEB-07using channel
   ORA_DISK_1Finished implicit crosscheck copy at 13-FEB-07searching for all files in the recovery areacataloging files...no
   files catalogedcataloged backuppiecebackup piece handle=/home/oracle/test/backup/o1_mf_annnn_TAG20070213T002925_2x21m6ty_.bkp
   recid=41 stamp=614393265RMAN> catalog backuppiece '/home/oracle/test/backup/o1_mf_annnn_TAG20070213T002825_2x21kbds_.bkp';cataloged
   backuppiecebackup piece handle=/home/oracle/test/backup/o1_mf_annnn_TAG20070213T002825_2x21kbds_.bkp recid=42 stamp=614393292RMAN>
   catalog backuppiece '/home/oracle/test/backup/o1_mf_nnndf_TAG20070213T002827_2x21kd12_.bkp';cataloged backuppiecebackup
   piece handle=/home/oracle/test/backup/o1_mf_nnndf_TAG20070213T002827_2x21kd12_.bkp recid=43 stamp=614393310
   

8. Get to know the last sequence available in the archivelog backup using the following command.
   
   RMAN > list backup of archivelog all;

9. Rename the Redologfiles,so that they can be created in new locations when opened the database is opened in resetlogs.
   
   SQL> alter database rename file '/u01/oracle/product/oradata/ora10g/log/redo01.log' to '/home/oracle/test/log/redo01.log';..................

10. Now restore the datafiles to new locations and recover.
    
    RMAN> run { set until sequence <seq_no> set newname for datafile 1 to '/home/oracle/test/data/sys01.dbf';
    set newname for datafile 2 to '/home/oracle/test/data/undotbs01.dbf'; set newname for datafile 3 to '/home/oracle/test/data/sysaux01.dbf';
    set newname for datafile 4 to '/home/oracle/test/data/users01.dbf'; set newname for datafile 5 to '/home/oracle/test/data/1.dbf';
    set newname for datafile 6 to '/home/oracle/test/data/sysaux02.dbf'; set newname for datafile 7 to '/home/oracle/test/data/undotbs02.dbf';
    restore database; switch datafile all; recover database; alter database open resetlogs; }
    

Here, Rampant TechPress author Kamran Agayev describes how to copy or clone a database using RMAN. 

Steps to clone a database using RMAN:

1: Create a password file on the destination server

2: Establish connectivity between the target and destination server (tnsnames.ora, sqlnet.ora)

3: Create the directories for the database files

4: Take the RMAN backup from the target server and copy it to the destination server.

5: Startup the destination database in nomount mode

6: Run the RMAN duplicate database command

Also see my notes on the 12c RMAN noopen clause.

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