9
Adding Instances and Nodes

This chapter describes how to convert from a single instance Oracle8i database to a multi-instance Oracle8i database using the Oracle Parallel Server Option, and how to add nodes to an existing configuration.

Specific topics discussed are:

• Moving from a Single Instance to Parallel Server

• Adding Additional Nodes to a Cluster

Moving from a Single Instance to Parallel Server

This section explains how to enable your database structure to support multiple instances. It also explains how to begin a project with a single instance Oracle database even though you intend to migrate to the multi-instance parallel server. In addition, this chapter can help you extend an existing Oracle Parallel Server configuration to additional nodes. This sections covers the following topics:

• Deciding to Convert

• Preparing to Convert

• Converting the Database from Single- to Multi-instance

Deciding to Convert

You may decide to convert to a multi-instance database when you have designed your application with Oracle Parallel Server in mind.

Do not convert to Oracle Parallel Server in the following situations:

• You are using a file system that is not shared.

• Your application was not designed for parallel processing; you need to examine your application more.

• You are not using a supported configuration (of shared disks, and so on).

Preparing to Convert

This section contains the following sections:

• Hardware and Software Requirements

• Converting the Application from Single- to Multi-Instance

• Administrative Issues

Hardware and Software Requirements

To convert to Oracle Parallel Server you must have:

• A supported hardware and OS software configuration

• A license for the Oracle Parallel Server

• Oracle8i Enterprise Edition running on all nodes

• Oracle Parallel Server linked to your system

Converting the Application from Single- to Multi-Instance

Making your database run in parallel does not automatically mean you have effectively implemented Oracle Parallel Server. Besides migrating your existing database from single instance Oracle to multi-instance Oracle, you must also migrate existing applications that were designed for single-instance Oracle. Preparing an application for use with a multi-instance database may require application partitioning and physical schema changes.

See Also: Oracle8i Parallel Server Administration, Deployment, and Performance for a full discussion of this topic

Administrative Issues

Note the following administrative issues of conversion:

• Your backup procedures should be in place before converting from single-instance Oracle to the Oracle Parallel Server.

• Additional archiving considerations apply in an Oracle Parallel Server environment. In particular, the archive file format needs the thread number. Furthermore, archived logs from all nodes are needed for media recovery. If you archive to a file, then on systems where file systems cannot be shared, some method of accessing the archive logs is required.

Converting the Database from Single- to Multi-instance

The following procedure explains how to migrate an existing database from single-instance Oracle to multi-instance Oracle. Remember that you must also migrate the application from single- to multi-instance.

To migrate from a single instance to an Oracle Parallel Server, perform the following tasks:

Task 1: Configure Hardware

Task 2: Evaluate Tablespaces and Log Files of Single Instance

Task 3: Create Raw Devices

Task 4: Export Data from Old Database

Task 5: Install Operating System Dependent Files

Task 6: Install Oracle8i Enterprise Edition and Oracle8i Parallel Server

Task 7: Create the Database

Task 8: Transfer Data From Old Data to Empty Database

Task 9: Start the Database

Task 1: Configure Hardware

See your vendor documentation for information about setting up Oracle Parallel Server hardware.

Task 2: Evaluate Tablespaces and Log Files of Single Instance

Because tablespaces must be identical on the Oracle Parallel Server as a single instance database, it is important that you do any consolidation, addition, or renaming of tablespaces on the single instance at this time.

Each additional node in the cluster requires two log files. Typically, a single instance database only has two log files. You must add additional log files for each node using the ALTER DATABASE ADD LOGFILE statement.

Task 3: Create Raw Devices

Create the raw devices needed for the data files, control files, and log files for Oracle Parallel Server, as explained in "Setting Up Raw Devices".

Task 4: Export Data from Old Database

Export the entire database from the single instance database. Use a tool such as the Export utility

To use the Export utility to export all data from an existing database to the new database:

Note: To export an entire database, you must use the user name SYSTEM. Do not use INTERNAL or SYS.

Run the Export utility:

exp username/password file=file.dmp full=y log file.log

file.dmp represents the data from the full database export of the database, while file.log represents the log of the operation.

See Also: Oracle8i Utilities for further information about this tool

Task 5: Install Operating System Dependent Files

For all nodes, see your Operating System Dependent vendor documentation for instructions about installing Operating System Dependent files.

Task 6: Install Oracle8i Enterprise Edition and Oracle8i Parallel Server

Except on the server already running Oracle8i Enterprise Edition, install Oracle8i Enterprise Edition along with the Oracle Parallel Server option, as described in Chapter 3. If your current single instance database does not have the supporting hardware, perform a clean install on new cluster hardware.

On the server already running Oracle8i Enterprise Edition, install Oracle Parallel Server using the Custom installation type.

Task 7: Create the Database

Create a new database on the raw partitions. Depending on the install type and subsequent configuration options, a database may be created with the following methods:

• If you selected the Typical installation, the database will be created after installation.

• If you requested that Oracle Database Configuration Assistant run after the Custom installation, Oracle Database Configuration creates a database.

• If you requested that Oracle Database Configuration Assistant not run after during Custom installation, you can still run Oracle Database Configuration to create a database, as described in "Use Oracle Database Configuration Assistant in Stand-Alone Mode".

• If you requested that Oracle Database Configuration Assistant not run during Custom installation, you can create the database manually, as described in "Use Manual Methods".

Task 8: Transfer Data From Old Data to Empty Database

Import the entire database into the empty database. Use a tool such as the Import utility.

To run the Import utility:

imp system/password file=file.dmp full=y log file.log

file.dmp represents the data from the full database export of the database, while file.log represents the log of the operation.

See Also: Oracle8i Utilities for further information about this tool

ATTENTION: If the original database from which the export file was generated contains tablespaces that are not in the new database, then the Import utility attempts to create those tablespaces with associated data files. The easy solution is to ensure both databases contain the same tablespaces. The data files do not have to be identical. Only the tablespace names need to be the same.

Task 9: Start the Database

See "Starting the Database in Parallel Mode" to start the Oracle Parallel Server.

Adding Additional Nodes to a Cluster

If you have already configured cluster and want to add other nodes, Oracle recommends the follow procedure:

1. Install another database into a different Oracle home that includes all the nodes you want to support, as described in Chapter 3.

2. Export the data from the existing database, as described in "Task 4: Export Data from Old Database".

3. Import the data to the new database, as described in "Task 8: Transfer Data From Old Data to Empty Database".