Converting Single instance to RAC instance Database Using DBCA

There are different ways to convert a single instance database to RAC.

1) Manual Method

2) Using rconfig

3) Using DBCA

4) Using grid control

In this post we will see step by step method to convert a single instance database to RAC Using DBCA(Database Configuration Assitant).

In this example, I already configured two node oracle asm, clusterware homes. also i already  converted the file system from non-asm to asm 
For converting filesystem to ASM click the link above.

follow steps for creating a template to convert a single instance to rac instance.

[oracle@rac1 ~]$ dbca &

Screen Name	Response
Welcome Screen	Select Single Instance database.
Operations	Select Manage Templates.
Template management operation	Select From an existing database(structure as well as data).
Choose the database	Select Database instance: testing
Specify the name and description	example: testing and description testing_database_convert_from_single_to_rac_instance_database
specify whether you want to convert all database  related file locations to OFA, or You want to main the file locations in the template.	Select Maintain the file locations.  and click FINISH.
The following operations will be performed: create a clone template from the source database.	click ok
Do you want to perform another operation	Click No to EXIT

Templates for existing single instance database has been created.

Go to $ORACLE_HOME/assistants/dbca/templates and check generated backup of single instance.

[oracle@rac1 templates]$ pwd
/u01/app/oracle/product/10.2.0/db_1/assistants/dbca/templates
[oracle@rac1 templates]$ ls -ltr
total 213584
-rw-r-----  1 oracle oinstall    12050 May 16  2005 New_Database.dbt
-rw-r-----  1 oracle oinstall     5728 Jun 30  2005 Data_Warehouse.dbc
-rw-r-----  1 oracle oinstall     5665 Jun 30  2005 Transaction_Processing.dbc
-rw-r-----  1 oracle oinstall     5608 Jun 30  2005 General_Purpose.dbc
-rwxr-xr-x  1 oracle oinstall  7061504 Jul  2  2005 Seed_Database.ctl
-rwxr-xr-x  1 oracle oinstall 93569024 Jul  2  2005 Seed_Database.dfb
-rwxr-xr-x  1 oracle oinstall   991232 Jul  2  2005 example.dmp
-rwxr-xr-x  1 oracle oinstall 13017088 Jul  2  2005 example01.dfb
-rw-r-----  1 oracle oinstall 96714752 Jul 27 13:47 testing.dfb
-rw-r-----  1 oracle oinstall  7061504 Jul 27 13:47 testing.ctl
-rw-r-----  1 oracle oinstall     5349 Jul 27 13:49 testing.dbc

Copy the pre-configured database image from rac1 machine $ORACLE_HOME/assistants/ dbca/ templates/ testing.dbf & testing.dbc    to  host rac2 environment  $ORACLE_HOME/assistants/dbca/templates/ folder

[oracle@rac1 templates]$ scp testing.dfb oracle@rac2:/u01/app/oracle/product/10.2.0/db_1/assistants/dbca/templates/
testing.dfb                                   100%   92MB   2.5MB/s   00:37
[oracle@rac1 templates]$ scp testing.dbc oracle@rac2:/u01/app/oracle/product/10.2.0/db_1/assistants/dbca/templates/
testing.dbc                                   100% 5349     5.2KB/s   00:00
[oracle@rac1 templates]$ scp testing.ctl oracle@rac2:/u01/app/oracle/product/10.2.0/db_1/assistants/dbca/templates/
testing.ctl                                   100% 6896KB   2.2MB/s   00:03

[oracle@rac2 templates]$ pwd
/u01/app/oracle/product/10.2.0/db_1/assistants/dbca/templates
[oracle@rac2 templates]$ ls -ltr
-rw-r-----  1 oracle oinstall 96714752 Jul 27 14:24 testing.dfb
-rw-r-----  1 oracle oinstall     5349 Jul 27 14:26 testing.dbc
-rw-r-----  1 oracle oinstall  7061504 Jul 27 14:26 testing.ctl

Start the dbca to convert the single instance to rac single database.
[oracle@rac2 templates]$ dbca &

Screen Name	Response
Welcome to the Database configuration assitant	Select Oracle Real Application Database
Select the operation	select : create a database
Select the nodes on which you want to create the cluster database	Select select all.
Select a template from the following list to create the database:	Select the template: testing(template name created by you)
Select the Global database name and SID:	Type name as you want, eg: raj.
Each oracle database may be managed centrally using the Oracle Enterprise Manager Grid Control or locally using the Enterprise Manager Database Control. Choose the management option that you would like to use to manage this database.	Select:  configure the database with enterprise manager
For security reasons, you must specify password for the following user accounts in the new database.	select: Use the same password for ALL accounts password: yourpassword confirm password: yourpassword
Select the Listeners	Select:Register this database with all listeners
Select the storage mechanism	Select: Automatic Storage Management(ASM)
select the disk groups to be used as storage for the database.	Select the disk group names: eg: DATA
Specify locations for the database files to be created.	Select:  use Oracle-Managed Files
Choose the recovery options	uncheck all
Custom Scripts	Select: No scripts to run
Oracle Database Services Details	Click: Next
Initialization Parameters	Click: Next
Database storage	Click: Next
creation options	click: Finish

[oracle@rac2 templates]$ vi /etc/oratab
edit the oratab file for instances raj as raj1 and raj2 on both nodes
[oracle@rac2 templates]$ . oraenv
ORACLE_SID = [oracle] ? raj2
[oracle@rac2 templates]$ sqlplus '/as sysdba'

SQL*Plus: Release 10.2.0.1.0 - Production on Tue Jul 27 19:37:27 2010

Copyright (c) 1982, 2005, Oracle.  All rights reserved.


Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning, Real Application Clusters, OLAP and Data Mining options

SQL> select instance_name from gv$instance;

INSTANCE_NAME
----------------
raj2
raj1

hope, this helps you.

related documents:
http://oracleinstance.blogspot.com/2009/12/convert-single-instance-to-rac-instance.html (rconfig method)
http://oracleinstance.blogspot.com/2009/12/migrate-from-database-file-system-to.html
http://oracleinstance.blogspot.com/2009/12/convert-rac-instance-to-single-instance.html