Oracle Essentials [Electronic resources] : Oracle Database 10g, 3rd Edition نسخه متنی

3.1 Installing Oracle

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.

Figure 3-1. Oracle Universal Installer

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.

3.1.1 Optimal Flexible Architecture (OFA)

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.

3.1.2 Supporting Multiple Oracle Versions on a Machine

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.

3.1.3 Upgrading an Oracle Database

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.