Oracle Database Cloning:
Larry Catt
Larry.catt@platinumsolutions.com
Cloning and 10g DBCA:
With the release of 10g, a database can be cloned from one location to another by use of the Oracle database Creation Assistant. However, this feature along with many of the new 10g features is worrisome to the veteran database administration crowd. The main reason for this worry is the lack of knowledge our junior associates are getting due to the new EM tool. They are not able to function in a telnet environment and trying to get them to perform any tasks using SQL*Plus is nearly impossible. Do not miss our point. The new EM tool provided by Oracle is a great improvement over past enterprise manager versions, however every tool has its place and a DBA must know far more than a GUI. The instruction set detailed below for the cloning of an oracle database is valid in multiple versions of Oracle from 8.1.5 to 10g and has the added benefit of being performed over a telnet or ssh connection.
Reason for Cloning:
In every oracle development and production environment there will become the need to transport the entire database from one physical machine to another. This copy may be used for development, production testing, beta testing, etc, but rest assured that this need will arise and management will ask you to perform this task quickly. Listed below are the most typical uses:
1. Relocating an Oracle database to another machine.
2. Moving Oracle database to new Storage media.
3. Renaming Oracle database.
Instructions:
1. Ensure that your database is recoverable back to original location and state by backing it up before executing this procedure:
Database in NON-ARCHIVE LOG MODE - take an off-line database backup.
Database in ARCHIVELOG MODE - take an on-line or off-line database backup.
2. Connect to sql*plus as the user ‘SYS AS SYSDBA’ and ensure that all users have logged off the system by executing the following command.
SQL> connect / as sysdba
Connected.
SQL> select username from v$session;
SQL> select username from v$session;
USERNAME
------------------------------
SYS
8 rows selected.
SQL>
You should see several fields returning with no username (these are internal oracle logins and the will not affect your operations) and one SYS login (this is you).
3. Place the system in restricted mode:
SQL> alter system enable restricted session;
System altered.
4. Connect as SYS with SYSDBA privileges and execute the following SQL command:
SQL> connect / as sysdba
Connected.
SQL> alter database backup controlfile to trace;
SQL>
The [alter database backup controlfile to trace;] command will generate a SQL script that can be used to regenerate the database.
5. Execute the sql*plus command show parameter
SQL> show parameter user_dump_dest
NAME TYPE VALUE
-------------------------- ----------- ------------------------------
user_dump_dest string /opt/app/oracle/product/admin/orcl/udump
6. Exit to the OS layer and move to the user_dump_dest directory. Trace file names are generated by oracle in the following format [instance_name]+[oracle generated number].trc, so use the timestamp to locate the last trace file generated. Open the file in a text editor and remove everything above the ‘STARTUP NOMOUNT ..' statement. Alter the ‘CREATE CONTROLFILE’ statement for the following uses:
Rename DB in Archivelog mode:
CREATE CONTROLFILE SET DATABASE "new_db_name" RESETLOGS
ARCHIVELOG
Rename DB in Non-Archivelog mode:
CREATE CONTROLFILE SET DATABASE "new_db_name" NORESETLOGS
NOARCHIVELOG
Reuse DB name in Archivelog mode:
CREATE CONTROLFILE REUSE DATABASE "db_name" RESETLOGS ARCHIVELOG
Reuse DB name in Non-Archivelog mode:
CREATE CONTROLFILE REUSE DATABASE "db_name" NORESETLOGS
NOARCHIVELOG
7. Edit the rest of this file to reference the correct locations of you log files, datafiles and temp files.
8. Move the trace file to an appropriate location and name to recreate_db.sql.
9. Connect as SYS with SYSDBA privileges and shutdown the database in immediate mode:
SQL> connect / as sysdba
Connected.
SQL> shutdown immediate
10. Move the following files to there corresponding locations in updated recreate_db.sql file.
DATAFILES
Log files
NOTE: Do not move your old control files or temp files to the new location.
11. Restore or copy the backup and the archived logs (if any) to the new machine.
12. Move your INIT$ORACLE_SID.ORA file to its new location. Ensure your controlfile and archive destinations in INIT are set properly to the new locations.
13. Connect to SQLPLUS on your new machine as SYS AS SYSDBA and run create_db.sql script as follows:
SQL> @[directory_location]/create_db.sql
14. Change the global database name if you renamed your database as follows:
SQL> ALTER DATABASE RENAME GLOBAL_NAME = new_db_name;
15. Perform full system backup and store in a safe location.
NOTE: This new backup will be you starting point for recovery in the new database location.
You have completed database cloning procedure.
For assistance with Oracle Products, you can contact Larry.catt@Platinumsolutions.com.
