6
Using Multiple Oracle Homes

This chapter describes how you work with multiple Oracle homes.

Specific topics discussed are:

• Multiple Oracle Homes Overview

• What Is Different About a Multiple Oracle Home Environment?

• Which Products Are Multiple Oracle Home Enabled?

• Product Installation Recommendations

• Working with Multiple Oracle Homes

  Warning: If you quit Oracle installer after you have entered the name and location for an Oracle home (for example, you need to quit Oracle Installer because you have insufficient disk space in the location specified), you will not be able to specify a different location for that home until you identify and delete the HOMEID key and the IDx key that corresponds to that Oracle home from the registry. To do this: Read the value of the ORACLE_HOME_NAME parameter for each HOMEID subkey in the HKEY_LOCAL_MACHINE\ SOFTWARE\ORACLE key until you find the value that matches the name of the Oracle home you need to delete. Delete the HOMEID subkey you have just identified. Delete the appropriate IDx subkey located in the HKEY_LOCAL_MACHINE\SOFTWARE\ORACLE\ ALL_HOMES key where x has the same value as the ID in HOMEID. For example, if the HOMEID subkey for the home name you want to delete is HOME1, then the appropriate IDx subkey is ID1. For more information on the registry keys and subkeys, see Appendix C, "Configuration Parameters and the Registry".

Multiple Oracle Homes Overview

An Oracle home corresponds to the environment in which Oracle products run. This environment includes:

• location of installed product files

• PATH variable pointing to the products' binary files

• registry entries

• service names

• program groups

Oracle homes also have a name, and a language associated with them. You specify the name, location, and language of an Oracle home at installation.

Releases of Oracle for Windows NT and Windows 95 prior to release 8.0.4 supported single Oracle homes, allowing you to install and run Oracle products in a single Oracle home. Different releases of Oracle products could be installed in the same Oracle home provided they had different second-digit release numbers. For example, you could install release 7.2 products and release 7.3 products in the same Oracle home. However, you could not install multiple third-digit releases of the same products. For example, you could not install release 7.3.2 and release 7.3.3 releases of the same Oracle products on the same computer; one installation would overwrite the other.

The Multiple Oracle homes feature enables you to install one or more releases of Oracle products on the same computer in multiple Oracle homes. For example, with multiple Oracle homes, you can install release 8.0.6, 8.0.5, and 8.0.4 products in different Oracle homes on the same computer. You can still install different releases of Oracle products in the same Oracle home provided they have different second-digit release numbers.

Why Use Multiple Oracle Homes?

The main benefit of using multiple Oracle homes is that you can run multiple releases of the same products concurrently. For example, you can test an 8.x.x database patch, before you run your production database 8.x.x against it.

When using third-party tools on your computer, if one tool is certified against release 8.x.1.x while another tool is certified against release 8.x.2.x, you may want to use the multiple Oracle homes feature so that you can install each third-party tool in a separate home.

When Should I Not Use Multiple Oracle Homes?

If you have previously installed release 8.0.x software and have no reason to keep the old release, overwrite the existing release by installing the 8.0.6 products in the home used for the previous release.

Warning: Multiple Oracle homes functionality only works with releases 8.0.4 and higher. If you have, for example, release 7.3.3 products already installed on your computer, you cannot install release 7.3.4 products in a separate Oracle Home. However, you can install release 8.0.6, 8.0.5, or 8.0.4 in the same home in which release 7.3.3 or 7.3.4 is installed and the version 7 release will be left intact.

What Is Different About a Multiple Oracle Home Environment?

If you decide to use multiple (versus single) Oracle homes, note these differences:

Element	First Oracle Home	Each Additional Oracle Home
Service Names	OracleTNSListener80	Includes the Oracle home name in service names, for example: OracleHOME_NAMETNSListener80
Program Groups	Oracle for Windows NT	Appends the Oracle home name to the program group, for example: Oracle for Windows NT - HOME_NAME
Registry Entries	Located in HKEY_LOCAL_MACHINE\SOFTWARE\ORACLE	Subkeys for each Oracle home added below the HKEY_LOCAL_MACHINE\ SOFTWARE\ORACLE subkey (HOME0, HOME1, HOME2, and so on). For more information on the registry keys and subkeys, see Appendix C, "Configuration Parameters and the Registry".
SID for starter database	ORCL	Only the first starter database on your computer is called ORCL. Additional starter databases use the naming convention ORCx or ORxx where x is a number appended to ensure the SID is unique.

Which Products Are Multiple Oracle Home Enabled?

The products included on your CD-ROM are classified as follows:

• Multiple Oracle Home Enabled

• Multiple Oracle Home Compliant

• Non-Multiple Oracle Home

Multiple Oracle Home Enabled

You can install products multiple times in multiple Oracle homes. Products are multiple Oracle home enabled unless they are listed in "Multiple Oracle Home Compliant Products" or "Non-Multiple Oracle Home Products".

Note: Oracle Intelligent Agent is a multiple Oracle homes enabled product. However, although it can be installed multiple times, only one version can be running at a time.

Multiple Oracle Home Compliant

You can install products into any Oracle home, but only once per computer. When installing any of these products, if other releases are detected on your computer, you are prompted to:

• continue installation without installing the product.

• quit the installation so that you can delete the existing release before proceeding to install the new release.

Multiple Oracle Home Compliant Products

When installing groups of products, if any of the products listed below are included in the group and already exist on the computer, they will not be installed. You must first deinstall pre-existing copies of these products (which may break other applications) before you can install them in a different home.

• Oracle Enterprise Manager

• Oracle Enterprise Manager SDK

• Oracle Enterprise Manager DB Admin Applications

• Oracle Administrator Toolbar

• Oracle Replication Manager

• Oracle Web Server Manager

• Oracle Security Server Manager

• Oracle SNMP Support

• Oracle File Packager

• Open Database Connectivity Driver (ODBC)

• Oracle Objects for OLE

• Oracle SNMP Agent

• Oracle Migration Assistant for Microsoft Access

• Oracle8 ConText Cartridge System Administration

• Oracle8 Performance Monitor

• Oracle Parallel Server

• All products that are dependent on any of the products listed above

Non-Multiple Oracle Home

You can only install these products into an old-style Oracle home (pre-8.0.4 Oracle home).

Non-Multiple Oracle Home Products

All Oracle release 8.0.3 products and all Oracle7 Products are non-multiple Oracle home products.

Product Installation Recommendations

Installing Newer Oracle Components into Older Oracle Homes

Can I install newer releases of Oracle components into an Oracle home that contains older releases of these components?

Do not install the following components unless you are upgrading the database:

Do Not Install Release...	Into an Oracle Home Release...
8.0.6, 8.0.5, or 8.0.4	8.0.3
8.0.6 or 8.0.5	8.0.4
8.0.6	8.0.5

If you install these releases into older Oracle homes, Required Support Files of the newer release overwrite the Required Support Files of the previous database installation, breaking the previous database.

Instead, install release 8.0.6, 8.0.5 and 8.0.4 components into separate Oracle homes rather than a previous Oracle home if you want to maintain multiple versions. The following is an example scenario.

I am not ready to upgrade my local release 8.0.5 database yet, but I want to use Oracle Enterprise Manager 1.6 included on the Oracle8 Enterprise Edition release 8.0.6 for Windows NT CD-ROM. I installed Oracle Enterprise Manager release 1.6 into the Oracle home where release 8.0.5 resides, but now my 8.0.5 database no longer works. What is wrong?

Products that depend on Required Support Files release 8.0.6 for example, Oracle Enterprise Manager release 1.6, cannot be installed into an Oracle home where a release 8.0.5 database already exists. Required Support Files release 8.0.6 overwrite Required Support Files release 8.0.5 and break the release 8.0.5 database.

If you want to install Oracle Enterprise Manager release 1.6 in the same Oracle home as your database, you need to upgrade your release 8.0.5 database to release 8.0.6. If you do not want to upgrade your database, Oracle Corporation suggests installing Oracle Enterprise Manager into a new Oracle home to avoid the Required Support Files release 8.0.6 overwriting the Required Support Files release 8.0.5. Since Oracle Enterprise Manager can only be installed in one Oracle home, you must deinstall it first before installing into a new Oracle home.

Working with Multiple Oracle Homes

Unless you specify otherwise at installation time, the Oracle home in which you installed products most recently is the first directory listed in your PATH (primary home). As such, it has priority over the other Oracle home entries in your PATH. If you invoke a product from the MS-DOS command prompt, the release of the product invoked will be that stored in the Oracle home listed first in your path, unless you specifically invoke a different release of the product by:

• specifying the full pathname to the release of the product you want to use at the command line

• changing your PATH so that the first entry points to the binary files for the product release you want to use. See "Changing the Value of PATH" for more information.

• changing to the directory that contains the executable you want to use

Changing the Value of PATH

You can change the value of PATH:

• using Oracle Home Selector.

• at the system level. The new value you assign to PATH exists until you change the value of PATH again.

• at the command line. The value of PATH reverts to its previous value when you quit the session.

  Note: The first two methods of changing the value of PATH are only valid if you are a member of the Administrators group. After you have changed the value of PATH, you must open a new MS-DOS window to make it active. The change is not reflected in already opened MS-DOS windows.

To change the value of PATH using Oracle Home Selector:

Oracle Home Selector is a graphical user interface (GUI) tool that enables you to edit your environment path to make an appropriate Oracle home directory your primary home. This tool can only be used when you have multiple, active Oracle home directories on a single computer.

1. Choose Start > Programs > Oracle for Windows NT - [HOME_NAME] > Oracle Home Selector.

   The Oracle Home Selector window appears.

2. Select the Oracle home that you want as the primary Oracle home from the drop-down list.

To change the value of PATH at the system level:

On Windows NT:

1. Choose Start > Settings > Control Panel.

   The Control Panel window appears.

2. Double-click the System icon.

   The System Properties window appears.

3. Click the Environment tab.

   The System Variables appear.

4. Edit the value of the PATH in the Value field and click OK to exit.

On Windows 95:

1. Open the AUTOEXEC.BAT file.

2. Edit the value of the PATH statement.

3. Reboot your computer.

On Windows 98:

1. Open the AUTOEXEC.BAT file.

2. Edit the value of the PATH statement.

3. Reboot your computer.

To change the value of PATH at the command line:

At the command prompt enter:

C:\> PATH PATHNAME;%PATH%

where PATHNAME is the full path to the binary files for the products you want to use. This change is valid for the current session only. If you want to change the value of your PATH more permanently, use the Oracle Home Selector or change the value of PATH at the system level. Both methods are described above.