3 Creating Oracle Real Application Clusters Databases with Database Configuration Assistant

3.1 Using Database Configuration Assistant with Oracle RAC

DBCA has the following primary database functions:

• Create and delete the database

• Add and delete database instances

• Set up network configuration for the database and its instances

• Register the database in Oracle Enterprise Manager Grid Control or configure Database Control

• Start up the database and its instances

  Note:

  Cluster Managed Services are no longer managed through DBCA. Instead, use the cluster managed services page in Oracle Enterprise Manager DB Control (accessible from the Cluster Database Availability Page). For more information, refer to Oracle Real Application Clusters Administration and Deployment Guide.

In addition DBCA has the following primary ASM functions:

• Configure and delete Automatic Storage Management (ASM)

• Provide an ASM instance for an Oracle Database node that is added to an existing Oracle RAC database that uses ASM, if ASM is not already configured on the node that is added to the Oracle RAC database

• Automatically extend an ASM instance on any node where you attempt to perform any ASM configuration operations (such as mount) on a node where ASM is not already configured

3.2 Benefits of Using Database Configuration Assistant

Oracle recommends that you use DBCA to create your Oracle RAC database, because preconfigured databases optimize your environment for features such as Automatic Storage Management (ASM), the server parameter file (SPFILE), and automatic undo management. DBCA also provides pages to create new ASM disk groups if they are needed. If you use ASM or cluster file system storage, then DBCA also configures automated backup, which uses the flash recovery area.

With DBCA, you can create site-specific tablespaces as part of database creation. If you have data file requirements that differ from those offered by DBCA templates, then create your database with DBCA and modify the data files later. You can also run user-specified scripts as part of your database creation process.

DBCA also configures your Oracle RAC environment for various Oracle high availability features, such as cluster administration tools. It also starts any database instances required to support your defined configuration.

3.3 Automatic Listener Migration from Earlier Releases

If your system has an Oracle Database 10g (10. 1) installation, and you install Oracle Database 11g release 1 (11.1) either to coexist with or to upgrade the Oracle Database 10.1 or 10.2 installation, then most installation types automatically migrate the Oracle Database 10.1 listener to the 11g release 1 (11.1) Oracle home. During migration, they configure and start a default Oracle Net listener using the same TCP/IP port as the existing listener, with the IPC key value EXTPROC. This process occurs through one of the following scenarios:

• During a coexisting installation, DBCA automatically migrates the listener and related files from the Oracle Database 10.1 or 10.2 Oracle home to the Oracle Database 11g Oracle home.

• During an upgrade, Oracle Database Upgrade Assistant (DBUA) automatically locates the Oracle 10g release 1 (10.1) or release 2 (10.2) listener, and migrates it to Oracle 11g release 1 (11.1).

The listener migration process stops the listener in the existing Oracle home, and restarts the listener from the new Oracle home. During migration, client applications may not be able to connect to any databases that are registered to the listener that is being migrated.

3.4 Verifying Requirements for DBCA

To help to verify that your system is prepared to create Oracle Database with Oracle RAC successfully, enter a Cluster Verification Utility (CVU) command using the following command syntax:

/CRS_home/bin/cluvfy.sh stage -pre dbcfg -n node_list -d Oracle_home [-verbose]

In the preceding syntax example, the variable CRS_home is the Oracle Clusterware home, the variable node_list is the list of nodes in your cluster, separated by commas, and the variable Oracle_home is the path for the Oracle home directory where OUI creates or modifies the database.

For example, to perform a check to determine if your system is prepared for an Oracle Database with Oracle RAC installation on a two-node cluster with nodes node1 and node2, with the CRS home path/u01/app/crs/, and with the Oracle home path /u01/app/oracle/product/11.1/db1, enter the following command:

$ /u01/app/crs/bin/cluvfy stage -pre dbcfg -n node1,node2 -d\
/u01/app/oracle/product/11.1/db1

You can select the option -verbose to receive progress updates as the CVU performs its system checks, and detailed reporting of the test results.

If the CVU summary indicates that the cluster verification check fails, then review and correct the relevant system configuration steps, and run the test again.

The command cluvfy.sh stage -pre dbcfg verifies the following:

• Node Reachability: All the specified nodes are reachable from the local node.

• User Equivalence: User equivalence exists on all the specified nodes.

• Node Connectivity: Connectivity exists between all the specified nodes through the available public and private network interfaces.

• Administrative Privileges: The oracle user has proper administrative privileges on the specified nodes for creating an Oracle RAC database.

• Oracle Clusterware Integrity: All the components of the Oracle Clusterware stack are fully operational.

3.5 Creating an Oracle RAC Database with DBCA

To create a database with DBCA in standalone mode without ASM or a cluster file system, you must have configured shared storage devices. In addition, you must have run the Oracle Net Configuration Assistant (NETCA) to configure your Oracle Net listener.ora file.

If you select DBCA templates that use preconfigured data files and if you do not use ASM or a cluster file system, then during database creation, DBCA first verifies that you created shared storage devices for each tablespace. If you have not configured the shared storage devices, then you must configure the devices and replace the default data file names that DBCA provides with the device names on the DBCA Storage page to continue database creation.

To start DBCA, connect as the oracle user to one of your nodes where Oracle RAC is installed, load SSH keys into memory, and enter the command dbca command from the $ORACLE_HOME/bin directory.

$ exec /usr/bin/ssh-agent $SHELL
$ /usr/bin/ssh-add

When you start DBCA, the first page it displays is the Welcome page for Oracle RAC, which includes the option to select an Oracle RAC database. DBCA displays this Oracle RAC Welcome page only if the Oracle home from which it is started was installed on a cluster.

If the Oracle RAC Welcome page opens, then provide information as prompted by DBCA. Click Help if you need assistance.

If DBCA does not display the Welcome page for Oracle RAC, then DBCA was unable to detect if the Oracle home is installed on a cluster. In this case, check that the OUI inventory is correctly located in the directory /etc/oraInst.loc, and that the oraInventory file is not corrupted. Also, perform clusterware diagnostics by using the following CVU command syntax:

/CRS_home/bin/cluvfy/runcluvfy.sh stage -post crsinst -n nodelist.

For example, with the mountpoint /u01/app/crs, and nodes node1 and node2, run the following command:

$ /u01/app/crs/bin/cluvfy.sh stage -post crsinst -n node1,node2

Note the following important information when using DBCA:

• If nodes that are part of your cluster installation do not appear on the Node Selection page, then run the opatch -lsinventory command to perform inventory diagnostics and clusterware diagnostics.

• The global database name can be up to 30 characters in length, and must begin with an alphabetic character. The domain portion of the global database name can be no more than 128 characters and can contain only alphabetic and numeric characters, as well as the period (.) character.

• The SID prefix must begin with an alphabetic character.

• The maximum number of characters you can use for the SID prefix is 8 characters. DBCA uses the SID prefix to generate a unique value for the variable ORACLE_SID for each instance.

• On the Management Options page, you are provided with selections for Oracle Enterprise Manager monitoring and management interfaces.

  Database Control is always an option. If DBCA discovers Grid Control agents on the cluster, then it also provides you with the option Enterprise Manager with the Grid Control. Choose between Database Control and Grid Control interfaces.

  You can set up e-mail notification and enable daily backup operations. For e-mail notifications, you provide the outgoing mail server and e-mail address. For daily backups, you enter the backup time and operating system credentials for the user that performs backup operations.

• To use a flash recovery area, Oracle recommends that you create at least two separate ASM disk groups: one for the database area and one for the recovery area. Oracle recommends that you place the database area and the recovery area in separate failure groups.

  A failure group is defined by shared hardware, such as a controller shared between two disks, or two disks that are on the same spindle. If two disks share hardware that could fail, making both disks unavailable, then these disks are said to be in the same failure group.

  If you do not use ASM, then Oracle recommends that the data files and the Flash Recovery area are located outside of the Oracle home, in separate locations, as with separate ASM failure groups, so that a hardware failure does not affect availability.

  See Also:

  Oracle Database Concepts for more information about using a flash recovery area, and Oracle Database Storage Administrator's Guide for information about failure groups and best practices for high availability and recovery

• On the ASM Disk Groups page, if you do not see the disks that you want to add, then click Change Disk Discovery Path to alter the search path used by DBCA to find available disks. You can select disks with a status of Candidate or Former (never used in an ASM disk group or no longer in a group) by selecting the check box. If you want to add disks that still have ASM disk headers, but the disk group is no longer in use (a case that can occur if you are selecting disks after an aborted install, you attempted deinstallation without dropping the disk group, or other configuration problems), then use the Force command.

• If DBCA displays the following message:

  The file oracle_home/bin/oracle does not exist on node node_name. 
  Make sure that file exists on these nodes before proceeding.
  

  This message means that the Oracle home from which the first ASM instance in the cluster runs is not installed on these cluster nodes. You must extend the ASM Oracle home to these nodes by performing the procedure documented in "Step 4: Adding Nodes at the Oracle RAC Database Layer" in the Oracle Real Application Clusters Administration and Deployment Guide. However, do not perform Step 5 in that section. OUI extends the ASM Oracle home to the selected nodes and performs any configuration required for running an ASM instance on these nodes.

• If DBCA displays the following message:

  Please run the DBCA from one of the nodes that has an existing ASM instance node_list.
  

  This message means that you are attempting to create an Oracle RAC database using ASM storage, but the ASM instance does not exist on the node from which you ran DBCA. However, ASM instances do exist on the remote nodes that appear in the message node list. In this case, DBCA cannot clone the existing ASM instance from the remote node to the local node. To correct this, start DBCA from one of the nodes shown in the node list to create your Oracle RAC database using ASM storage. This copies the local node's ASM instance and modifies its parameters and attributes to create ASM instances on the nodes in your cluster that do not have ASM instances.

• On the Recovery Configuration page, if you are using ASM or cluster file system storage, then you can also select the flash recovery area and size on the Recovery Configuration page. If you are using ASM, then the flash recovery area defaults to the ASM Disk Group. If you are using OCFS, then the flash recovery area defaults to $ORACLE_BASE/flash_recovery_area.

• On the Initialization Parameters page, if you are installing on a Linux system, note that Memory Size (SGA and PGA), which sets the initialization parameter MEMORY_TARGET or MEMORY_MAX_TARGET, cannot be greater than the shared memory filesystem (/dev/shm) on your operating system.

  For example, if the shared memory filesystem allocation on your system is 1 GB, but you set Memory Size (MEMORY_TARGET) to 2 GB, then you receive the following error during database startup:

  ORA-00845: MEMORY_TARGET not supported on this system 
  ORA-01078: Failure in processing system parameters
  

  This issue is not relevant for other platforms.

  For all platforms, if you intend to add more nodes in your cluster than you have during the current DBCA session, then click All Initialization Parameters, and change the parameter CLUSTER_DATABASE_INSTANCES to the number of nodes that you will add to the cluster.

  In addition, if you click All Initialization Parameters, note that if your global database name is longer than 8 characters, then the database name value (in the DB_NAME parameter) is truncated to the first 8 characters, and the DB_UNIQUE_NAME parameter value is set to the global name.

  See Also:

  Oracle Database Administrator's Reference for information about initialization parameters

After you respond to DBCA prompts, review the Summary dialog information and click OK, DBCA does the following:

• Creates an operative Oracle RAC database and its instances

• Creates the Oracle RAC data dictionary views

• Configures the network for the cluster database

• Migrates previous release Oracle Database listeners and related files to the Oracle Database 11g Oracle home

• Starts the listeners and database instances, and then starts the high availability services

• Configures Oracle Enterprise Manager Database Control or Grid Control

3.6 Deleting an Oracle RAC Database with DBCA

This section explains how to delete an Oracle RAC database with DBCA. This process deletes a database and removes a database's initialization parameter files, instances, OFA structure, and an Oracle network configuration. However, this process does not remove data files if you placed the files on raw devices or on raw partitions.

To delete a database with DBCA:

1. Start DBCA on one of the nodes:.

   • Run the DBCA command from the $ORACLE_HOME/bin directory.

   The DBCA Welcome page appears.

2. Select Oracle Real Application Clusters, and click Next.

   After you click Next, DBCA displays the Operations page.

3. Select Delete a database, and click Next. DBCA displays the List of Cluster Databases page.

4. If your user ID and password are not operating-system authenticated, then the List of Cluster Databases page displays the user name and password fields. If these fields appear, then enter a user ID and password for a user account that has SYSDBA privileges.

5. Select the database to delete, and click Finish.

   After you click Finish, DBCA displays a dialog box to confirm the database and instances that DBCA is going to delete.

6. Click OK to begin the deletion of the database and its associated files, services, and environment settings, or click Cancel to stop the operation.

When you click OK, DBCA continues the operation and deletes all the associated instances for this database. DBCA also removes the parameter files, password files, and oratab entries.

At this point, you have accomplished the following:

• Deleted the selected database from the cluster

• Deleted high availability services that were assigned to the database

• Deleted the Oracle Net configuration for the database

• Deconfigures Database Control

• Deleted the OFA directory structure from the cluster

• Deleted the data files if the data files were not on raw devices