RMAN Duplicate Database Feature in 11G

RMAN Duplicate Database Feature in 11G
You can create a duplicate database using the RMAN duplicate command. The duplicate database will have a different DBID from the source database and it functions entirely independently because it is completely independent once the duplication has taken place and the duped database is open for use.
Starting with Oracle 11g there are now two ways to duplicate a database:
1. Active database duplication2. Backup-based duplication
Active database duplication involves copying the live running database over the network to the auxiliary destination and creating the duplicate database. The backup-based duplication requires copying over using NFS to make available the backupset(s) to the destination database. The only difference between the two is you do not need pre-existing RMAN backups and copies (archivelogs). The duplication work is performed by the auxiliary channel and this channel corresponds to a server session on the auxiliary instance on the auxiliary (destination) host.
The active database duplication is slower because it is using the network to transport the data blocks instead of accessing existing RMAN backupsets. RMAN carries out the following steps as part of the duplication process:
1. Creates a control file for the duplicate database2. Restarts the auxiliary instance and mounts the duplicate control file3. Creates the duplicate datafiles and recovers them with incremental backups and archived redo logs4. Opens the duplicate database with the RESETLOGS option
In the case of active database duplication, RMAN copies the target datafiles over the network to the auxiliary (destination) instance.
A RAC Target database can be duplicated as well, this feature is not restricted to non-RAC databases. The procedure is the same as what is outlined below. If the auxiliary database needs to be a RAC-database then you start the process to duplicate a single instance and convert the auxiliary to RAC after the duplicate process has succeeded.
The next section is devoted to describing the process for Active Database Duplication.
Active Database Duplication
1. Prepare the auxiliary database instance2. Create the initialization parameter file for the Auxiliary instance
If you are using SPFILE then according to Oracle the only parameter required for the duplicate database is the DB_NAME parameter. The rest of the parameters can be set in the DUPLICATE command. If you are not using the SPFILE technique for your Oracle initialization parameter file then you will need to create an init.ora file and set the initialization parameters. Again according to Oracle the only required parameters are:
DB_NAMECONTROL_FILESDB_BLOCK_SIZEDB_FILE_NAME_CONVERTLOG_FILE_NAME_CONVERTDB_RECOVERY_FILE_DEST
However, I have found if I use a full meaning a copy of one of my running Database’s parameter file it is easier than specifying the parameters in the DUPLICATE command itself. That is a personal preference and you should go with whatever works best for you. I use SPFILE files for all my Oracle Databases and whenever I have a need to duplicate one of them I will generate (create) an init.ora initialization parameter file for use with RMAN. I will then use my favorite editor to search and replace the database specific parameters with my new Oracle Database parameters like DB_NAME, DB_RECOVERY_FILE_DEST, etc.
3. Create the Oracle Password file for the Auxiliary Instance – this is a requirement for RMAN in order to duplicate a database you need to connect directly to the auxiliary instance using the password file with the same SYSDBA password as the target database’s password. The passwords have to match exactly in order for this to work. You can specify the PASSWORD FILE option on the DUPLICATE command in which case if you do RMAN will copy the source database password file to the destination host and overwrite any existing password file with the same name as the auxiliary instance’s name.
4. Make the necessary changes to the listener.ora and tnsnames.ora file in order to establish SQL*Net connectivity before starting the RMAN duplicate session. You have to be able to connect through Oracle Net to the target and the auxiliary instance in order to use Active Database duplication.5. Start the Auxiliary instance from SQL*Plus – start the database and put it in nomount mode but first take care of the following steps:
I always create a link in $ORACLE_HOME/dbs to the initialization file and I just rename this link when I’m finished with RMAN to switch over to using a spfile instead of the pfile method. This way you do not have to type in a lot of characters whenever you stop, start the auxiliary instance because more than likely you will have to execute the process more than once unless you get it right the very first time! I set up the ADR – in Oracle 11G the new Automatic Diagnostic Recovery filesystem (if you aren’t using ADR set up the $ORACLE_BASE/admin/$ORACLE_SID/bdump/…._) directories prior to bringing up the auxiliary instance in nomount mode. You will need to create the supporting directories prior to starting the auxiliary instance.
Windows:
Create the parameter file (using Oracle’s example):
initNEW.oraDB_NAME=NEWdiagnostic_dest=’E:\opt\oracle’DB_FILE_name_CONVERT=(’I:\oradata\OLD’,'E:\oradata\NEW’)LOG_FILE_NAME_CONVERT=(’I:\oradata\onlinelog\OLD’,'E:\oradata\onlinelog\NEW’)SGA_TARGET=26214400CONTROL_FILES=’E:\oradata\controlfile\NEW\control01.dbf’COMPATIBLE=11.1.0.0.0
Create the Database Service (Windows Only) and password file:
% set ORACLE_SID=NEW% set ORACLE_HOME=E:\opt\app\oracle\product\11.1.0\db_1% oradim -NEW -SID NEW% orapwd FILE=E:\opt\app\oracle\product\11.1.0\db_1\database\PWPDNEW.ora PASSWORD=sys
% sqlplus “/ as sysdba”sql> startup nomount;
6. Create the necessary Oracle Net connectivity in the listener.ora and tnsnames.ora files – you need to make sure you specify SERVER = DEDICATED in the tnsnames.ora entry for your auxiliary instance and if you are using Oracle on HP-UX 11i v3 Itanium there is a bug that requires you to use the string ‘(UR=A)’ at the end of the tnsnames.ora entry (put it after the SERVICE_NAME entry). Confirm the connectivity to the target, auxiliary and you may want to confirm connectivity to your RMAN catalog even though you will not be using the catalog for this type of database duplication.
7. Start RMAN and connect to the source database by specifying the source as the target database. The duplicate database instance will be specified in the AUXILIARY connection. You can invoke the RMAN client on any host so long as that host has connectivity and you can connect to all of the required database instances. If the auxiliary instance requires a text-based initialization parameter file (pfile) then this file must exist and it must reside on the same host that runs the RMAN client application.
% rmanrman> connect target sys/sys@old;rman> connect auxiliary sys/sys
8. Next you will be issuing the DUPLICATE database command in order to start the duplicate process and the simplest case is when you duplicate the target database to a different host and use a different directory structure. This example will assume you are using a recovery catalog, the target database is on hosta and it contains four datafiles. You duplicate the target to database AUX on a different host (hostb) and hostb has a different directory structure. The tablespace USERS is a read-only tablespace for the purpose of this example. Execute the duplciate database command from the Auxiliary site:
rman duplicate target database to ‘NEW’ from active database db_file_name_convert ‘i:\oradata\OLD’,'e:\oradata\NEW’;
A dedicated listener configuration for RMAN is required. Using instance registration requires that the database be mounted in order to register with the listener. RMAN also requires SYSDBA access to the nomount instance (Auxiliary). The control files will be create using the location and names specified in the Oracle initialization file. The use of log_file_name_convert and db_file_name_convert instructs RMAN to generate the “set newname” commands for you. You can create your own set instead of using these two commands and you can use the ‘logfile’ command to specify where the log files will be created and what size they will be created with