Prior to Oracle8i, the Oracle installer came in both character and GUI versions for Unix. The Unix GUI ran in Motif using the X Windows system. Windows NT came with a GUI version only. Since Oracle8i, the installer is Java-based. The Oracle installer is one of the first places in which you can see the benefits of the portability of Java; the installer looks and functions the same across all operating systems. Installing Oracle is now quite simple, requiring only a few mouse clicks and answers to some questions about options and features.
Oracle has further simplified installation of Oracle Database 10g. This version of the database comes on a single CD-ROM, and can be installed in less than 30 minutes. Figure 3-1 shows a version of the launch screen of the installer for Oracle Database 10g.
Although the installation process is now the same for all platforms, there are still particulars about the installation of Oracle that relate to specific platforms. Each release of the Oracle Database server software is shipped with several pieces of documentation. Included in each release are an installation guide, release notes (which include installation information added after the installation guide was published), and a "getting started" book. You should read all of these documents prior to starting the installation process, because each of them contains invaluable information about the specifics of the installation. You will need to consider details such as where to establish the Oracle Home directory and where database files will reside. These issues are covered in detail in the documentation. In addition to the hardcopy documentation, online documentation is shipped on the database server CD-ROM, which provides additional information regarding the database and related products.
You'll typically find the installation guide in the server software CD case. The installation guide includes system requirements (memory and disk), pre-installation tasks, directions for running the installation, and notes regarding migration of earlier Oracle databases to the current release. You should remember that complete installation of the software includes not only loading the software, but also configuring and starting key services.
One of the more important decisions you need to make before actually installing Oracle concerns the directory structure and naming conventions you will follow for the files that make up a database. Clear, consistent, and well-planned conventions are crucial for minimizing human errors in system and database administration. Some of the more important conventions to consider include the following:
Disk or mount point names
Directory structures for Oracle software and database files
Database filenames: control files, database files, and redo log files
The Optimal Flexible Architecture, described in the next section, provides suggestions for naming conventions for all of these files.
There is one more piece of documentation that you may not know about, but may find extremely valuable in creating and managing your Oracle environment. Oracle consultants working at large Oracle sites created (out of necessity) a comprehensive set of standards for Unix directory structures and filenames. This set of standards is called An Optimal Flexible Architecture for a Growing Oracle Database or, as it is lovingly known in the Oracle community, the OFA. The OFA provides a clear set of standards for handling multiple databases and multiple versions of Oracle on the same machine. It includes recommendations for mount points, directory structures, filenames, and scripting techniques. Anyone who knows the OFA can navigate an Oracle environment to quickly find the software and files used for the database and the instance. This standardization increases productivity and avoids errors.
While the OFA was created for Unix, the core standards can be and have been applied to Windows and other operating systems. Through the later Oracle7 releases, the OFA standards were also embedded in the Oracle installer. All system administrators and database administrators working with Oracle will find the OFA worthwhile, even if your Oracle system is already installed. The OFA exists as part of the Oracle installation guide.
Oracle Managed Files, which were new in Oracle9i and were discussed in Chapter 2, use the OFA for their own internal naming conventions.
You can install and run multiple versions of Oracle on a single-server machine. All Oracle products use a directory referred to by the environment or system variable ORACLE_HOME to find the base directory for the software they will use. Because of this, you can run multiple versions of Oracle software on the same server, each with a different ORACLE_HOME variable defined. Whenever a piece of software accesses a particular version of Oracle, the software simply uses the proper setting for the ORACLE_HOME environment variable.
Oracle supports multiple ORACLE_HOME variables on Unix and Windows systems by using different directories. The OFA provides clear and excellent standards for this type of implementation.
Oracle Database 10g includes two additional features that will help you upgrade an existing Oracle database: the Database Upgrade Assistant and rolling upgrades.
If you want to upgrade a single instance, you can use the Database Upgrade Assistant, which can be started from the Oracle Universal Installer.
One of the longstanding problems with upgrades has been the requirement to bring down the database, upgrade the database software, and then restart the database. This necessary downtime can impinge on your operational requirements. If you are using a Real Application Clusters (RAC) implementation of Oracle Database 10g, you can perform a rolling upgrade. A rolling upgrade allows you to bring down some of the nodes of the cluster, upgrade their software, and then bring them back online as part of the cluster. You can then repeat this procedure with the other nodes. The end result is that you can achieve a complete upgrade of your Oracle database software without having to bring down the database.