3 Managing Oracle Homes

Target Home

The Oracle home currently accessed by OUI for installation or deinstallation is the target home. In order to upgrade or remove products from the target homes, those products must be shut down or stopped.

/Program Files/Oracle/Inventory (on Windows)
<user_home>/oraInventory (on UNIX)

Locating the Inventory on Windows Systems

On the Windows platform, OUI first queries the registry to see if the following Oracle home setting is present:

HKEY_LOCAL_MACHINE

Software

Oracle

inst_loc

If this value is found, it will be used as the inventory location. If the value is not found, and the $ORACLE_BASE environment variable is not specified, the following sequence occurs:

1. OUI requests the location of the Program Files directory. (The Program Files folder is a system-defined directory usually on the C drive.)

2. The OUI directory structure is created.

3. The registry is updated with this inventory location.

Locating the Inventory on UNIX

At startup, OUI first looks for the following file:

var/opt/oracle/oraInst.loc

If this value is found, it will be used as the inventory location. If the value is not found, and the $ORACLE_BASE environment variable is not specified, OUI prompts the user to supply a location for the inventory.

Home Selector Overview

The Home Selector is part of the installation software. The Home Selector enables you to easily change your primary Oracle home (the one that appears first in the PATH environment variable). If you need to switch the active home or need to perform batch work which requires a "default home" to be active, the Home Selector can be used to change the Windows NT system settings.

When using the Home Selector to make a specific $ORACLE_HOME the active one, the software installation in question is moved to the front of the PATH variable, making it the first directory to be scanned for executables and library files.

Use the GUI in the Environment tab of the Inventory dialog to establish the order of Oracle homes in your PATH variable.

How Home Selector Works

When you perform an install on a system, OUI runs the selectHome.bat file to register the Oracle home you selected. The first $ORACLE_HOME will be named the "DEFAULT_HOME" and will register itself in the Windows NT registry under the key:

HKEY_LOCAL_MACHINE

Software

Oracle

This is the default Windows NT registry hive which contains all the "generic" Oracle settings. Also the PATH variable is adjusted and the BIN directory of the $ORACLE_HOME is added to the environment variable.

Starting with Oracle 8.0.4, the first version to be multiple $ORACLE_HOME aware, some additional parameters will also be written to the key:

HKEY_LOCAL_MACHINE

Software

Oracle

Home0

With OUI, you can change the "DEFAULT_HOME" name to something else. Also, it registers all Oracle settings in the "Home0" subkey of the ORACLE key.

When an additional $ORACLE_HOME is added to the system, the PATH variable is adjusted again to add the new BIN directory of the newly installed Oracle software. The registry variables are written to a key named "HOMEx," where X is the next available number in the Oracle key.

When several $ORACLE_HOMEs are installed, the executables referenced are all found in the first $ORACLE_HOME\BIN directory of the PATH variable. When you want to switch the order of the PATH variable, you can use the Home Selector to switch the order of the $ORACLE_HOMEs installed on the system.

Together with the installation and registration of the software in the registry, a second series of registry variables are written in the following key:

HKEY_LOCAL_MACHINE

Software

Oracle

ALL_HOMES

This is the starting point for the list of all $ORACLE_HOME installations, done on this system.

The following variables are written in this key:

• HOME_COUNTER: Number of Oracle home directories already present on the system. This counter is a number, exactly 1 higher as the last ID subkey present.

• LAST_HOME: ID number of the currently active $ORACLE_HOME

• IDx: List of registry key's containing the name, number and installation directory of this ORACLE_HOME. The first installation is written in ID0, the next one in ID1, etc.

If the Home Selector is started in interactive mode, the registry hive "ALL_HOMES" is read, including all subkeys, and a dialog box will be displayed with all available installations. As soon as the you select one, the PATH variable will be adjusted at the system level.

The name of this $ORACLE_HOME is one of the names found in the ID subkeys.

Oracle Home Directory Structure for Windows Platforms

A typical Oracle home on Windows platforms contains the files and directories shown in Table 3-2.

Optimal Flexible Architecture Directory Structure (on UNIX)

The Optimal Flexible Architecture (OFA) standard is a set of configuration guidelines for fast, reliable Oracle databases that require little maintenance.

OFA is designed to:

• Organize large amounts of complicated software and data on disk to avoid device bottlenecks and poor performance

• Facilitate routine administrative tasks such as software and data backup functions, which are often vulnerable to data corruption

• Alleviate switching among multiple Oracle databases

• Adequately manage and administer database growth

• Help eliminate fragmentation of free space in the data dictionary, isolate other fragmentation, and minimize resource contention

The OFA directory structure is described below.