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?

• 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 the 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 want 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 versions of Oracle products could be installed in the same Oracle home provided they had different second-digit release numbers. For example, you could install version 7.2 products and version 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 versions of the same Oracle products on the same machine; one installation would overwrite the other.

This release includes the new multiple Oracle homes feature, which enables you to install one or more releases of Oracle products on the same machine in multiple Oracle homes. For example, with multiple Oracle homes, you can install version 8.0.3 products and 8.0.4 products in different Oracle homes on the same machine. You can still install different versions 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 third-digit versions 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 machine, 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 version, overwrite the existing version by installing the 8.0.4 products in the home used for the previous release.

WARNING: Multiple Oracle homes functionality only works with release 8.0.4. If you have, for example, release 7.3.3 products already installed on your machine, you cannot install release 7.3.4 products in a separate Oracle Home. However, you can install release 8.0.4 on a machine on 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 machine 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 either:

• 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 the "Multiple Oracle Home Compliant Products" or "Non-Multiple Oracle Home Products" sections below.

• Multiple Oracle Home Compliant

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

  • continue installation without installing the product
  • quit the installation so that you can delete the existing version before proceeding to install the new version.

• Non-Multiple Oracle Home

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

Multiple Oracle Home Compliant Products

• Oracle Enterprise Manager

• Oracle Enterprise Manager SDK

• Oracle Enterprise Manager DB Admin Applications

• Oracle Administrator Toolbar

• Oracle Replication Manager

• Oracle Web Server Manager

• Oracle Biometrics Manager

• Oracle Security Server Manager

• Oracle File Packager

• Oracle Intelligent Agent

• Open Database Connectivity Driver (ODBC)

• Oracle Objects for OLE

• Oracle Migration Assistant for Microsoft Access

• Oracle8 ConText Cartridge Workbench

• Oracle Parallel Server

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

When installing groups of products, if any of the products listed above are included in the group and already exist on the machine, 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.

Non-Multiple Oracle Home Products

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

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, the version of the product invoked will be that stored in the Oracle Home listed first in your path, unless you specifically invoke a different version of the product by:

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

• navigating to the program group that contains the version you require

• changing your PATH so that the first entry points to the binary files for the product version 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.

To change the value of PATH using Oracle Home Selector:

Oracle Home Selector is a graphical user interface (GUI) 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.

1. Select the Oracle home that you want to be 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.

1. Double-click the System icon.

   The System Properties window appears.

2. Click the Environment tab.

   The System Variables appear.

3. Edit the value of the PATH in the Systems Variables window and click OK to exit.

On Windows 95:

1. Open the AUTOEXEC.BAT file.

1. Edit the value of the PATH statement.

2. Reboot your machine

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, you should use the Oracle Home Selector or change the value of PATH at the system level. Both methods are described above.

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