Creating a copy of an Oracle RAC database
A copy of an Oracle RAC database can be created using the -createDuplicateDB command option -databaseConfigType with the value of RAC or RACONENODE.
A copy of an Oracle RAC database can be created using the -createDuplicateDB command option -databaseConfigType with the value of RAC or RACONENODE.
It has been possible to create a standby database using the createDuplicateDB DBCA command since 12.2.
18c added a new capability to specify the database configuration type of a new standby, such as: RAC, RAC One Node, or a regular single instance database.
This method by itself requires some prerequisite actions. I do not see that these are documented, so that I am writing this blog post.
Setup
Primary
- Hostname:
primary - db_name:
orcl - db_unique_name:
orcl - Configuration Type:
Single Instance
Standby
- Hostnames:
rac1.example.com, rac2.example.com - db_unique_name:
racdb - Configuration Type:
RAC - SCAN port:
1521 - Local listener port:
1522 - Grid Home:
/u01/app/19.3.0/grid,owner=grid - DB Home:
/u01/app/oracle/product/19.3.0/dbhome_1,owner=oracle(role separation) - ASM disk groups: single disk group
DATA- it is a sandbox
DBCA Command
This is a DBCA command that I will run to create a standby database in 19.9:
dbca -createDuplicateDB -silent \
-gdbName orcl \
-primaryDBConnectionString primary:1521/orcl \
-sid racdb \
-initParams "dg_broker_start=true" \
-sysPassword change_on_install \
-adminManaged \
-nodelist rac1,rac2 \
-recoveryAreaDestination +DATA \
-recoveryAreaSize 10000 \
-databaseConfigType RAC \
-useOMF true \
-storageType ASM \
-datafileDestination +DATA \
-createAsStandby \
-dbUniqueName racdb \
-createListener rac1.example.com:1522
Firstly, let me go over the keys that are worth mentioning.
-primaryDBConnectionString primary:1521/orcl- it should have a specific port number even if it is default 1521-createListener rac1.example.com:1522- this is the most interesting part. This is part of the RMAN block that is run to create a physical standby database:duplicate target database for standby from active database dorecover nofilenamecheck ;
It is the push-based method of active database duplication. Therefore, the primary database should be able to connect to the new standby. I specified the local listener endpoint (1522) in this example. Then, DBCA always tries to create a new listener in this configuration. I do not know how to avoid that here. Even worse, it attempts to create a new listener in DB home. Thankfully, it silently swallows an error if the listener already exists. Here is a sample excerpt from the DBCA log file to substantiate that remark with some facts:[progressPage.flowWorker] [ 2020-12-30 19:04:30.642 UTC ] [ClusterInfo.getHostName:462] Hostname = rac1 INFO: Dec 30, 2020 7:04:30 PM oracle.install.commons.system.process.ProcessLauncher launchProcess INFO: Executing [/u01/app/oracle/product/19.3.0/dbhome_1/bin/lsnrctl, start, rac1.example.com] INFO: Dec 30, 2020 7:04:30 PM oracle.install.commons.system.process.ProcessLauncher launchProcess INFO: Starting Output Reader Threads for process /u01/app/oracle/product/19.3.0/dbhome_1/bin/lsnrctl INFO: Dec 30, 2020 7:04:30 PM oracle.assistants.common.util.NetworkConfigHelper$2 processLine INFO: INFO: Dec 30, 2020 7:04:30 PM oracle.assistants.common.util.NetworkConfigHelper$2 processLine INFO: LSNRCTL for Linux: Version 19.0.0.0.0 - Production on 30-DEC-2020 19:04:30 INFO: Dec 30, 2020 7:04:30 PM oracle.assistants.common.util.NetworkConfigHelper$2 processLine INFO: INFO: Dec 30, 2020 7:04:30 PM oracle.assistants.common.util.NetworkConfigHelper$2 processLine INFO: Copyright (c) 1991, 2020, Oracle. All rights reserved. INFO: Dec 30, 2020 7:04:30 PM oracle.assistants.common.util.NetworkConfigHelper$2 processLine INFO: INFO: Dec 30, 2020 7:04:30 PM oracle.assistants.common.util.NetworkConfigHelper$2 processLine INFO: TNS-01106: Listener using listener name LISTENER has already been started INFO: Dec 30, 2020 7:04:30 PM oracle.install.commons.system.process.ProcessLauncher launchProcess INFO: The process /u01/app/oracle/product/19.3.0/dbhome_1/bin/lsnrctl exited with code 1 INFO: Dec 30, 2020 7:04:30 PM oracle.install.commons.system.process.ProcessLauncher launchProcess INFO: Waiting for output processor threads to exit. INFO: Dec 30, 2020 7:04:30 PM oracle.install.commons.system.process.ProcessLauncher launchProcess INFO: Output processor threads exited. INFO: Dec 30, 2020 7:04:30 PM oracle.assistants.common.util.NetworkConfigHelper startListener INFO: Exit code of lsnrctl is:1 INFO: Dec 30, 2020 7:04:30 PM oracle.assistants.dbca.driver.backend.steps.ListenerConfigStep createStaticListener INFO: Static listener created. INFO: Dec 30, 2020 7:04:30 PM oracle.assistants.dbca.driver.StepDBCAJob$1 update INFO: Percentage Progress got for job:Listener config step progress:100.0
There is another little drawback with this approach - it creates listener.ora in DB home which uses a static configuration. It is harmless, but I would rather clean it up after the exercise to have a nice and tidy environment.
Prerequisite Steps
It should be possible to establish a connection from the primary host using the local listener endpoint:rac1.example.com:1522.I do not discuss DNS setup - it is implied.
I need to configure a static registration for the new RAC instance. For that, I edit my GI listener.ora on the host I am going to run the duplicate command from (rac1):
# /u01/app/19.3.0/grid/network/admin/listener.ora
SID_LIST_LISTENER=
(SID_LIST=
(SID_DESC=
(SID_NAME=racdb1)
(ORACLE_HOME=/u01/app/oracle/product/19.3.0/dbhome_1)
)
)
That is basically it. Once I reload the local listener, I am good to continue to the next step.
Creating RAC Physical Standby
[oracle@rac1 ~]$ dbca -createDuplicateDB -silent \ > -gdbName orcl \ > -primaryDBConnectionString primary:1521/orcl \ > -sid racdb \ > -initParams "dg_broker_start=true" \ > -sysPassword change_on_install \ > -adminManaged \ > -nodelist rac1,rac2 \ > -recoveryAreaDestination +DATA \ > -recoveryAreaSize 10000 \ > -databaseConfigType RAC \ > -useOMF true \ > -storageType ASM \ > -datafileDestination +DATA \ > -createAsStandby \ > -dbUniqueName racdb \ > -createListener rac1.example.com:1522 Prepare for db operation 22% complete Listener config step 44% complete Auxiliary instance creation 67% complete RMAN duplicate 89% complete Post duplicate database operations 100% complete Look at the log file "/u01/app/oracle/cfgtoollogs/dbca/racdb/racdb.log" for further details.That is it:
SQL> select database_role from v$database; DATABASE_ROLE ---------------- PHYSICAL STANDBY SQL> select instance_name, host_name from gv$instance; INSTANCE_NAME HOST_NAME ---------------- -------------------- racdb1 rac1.example.com racdb2 rac2.example.com
Further Steps
- Delete
/u01/app/oracle/product/19.3.0/dbhome_1/network/admin/listener.ora. DBCA created this file with the following content:SID_LIST_RAC1.EXAMPLE.COM = (SID_LIST = (SID_DESC = (SID_NAME = racdb1) ) ) RAC1.EXAMPLE.COM = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = rac1.example.com)(PORT = 1522)) ) - Adding standby redo logs, creating a new Data Guard Configuration, enabling
FORCE_LOGGING, Flashback database, etc. - I do not mention it here. The purpose of this post to show how to instantiate a new RAC standby database in one command after completing some simple preliminary steps.
Notable Downsides
There ain't no such thing as a free lunch.Both slow connection between the sites, and a "huge" database size limits the applicability of this method.
I do not see how this method can utilize the restartable duplication too.
In all other cases, it is possible to quickly spin up a new RAC standby database using this excellent DBCA createDuplicateDB command.
