3
Multiple Oracle Homes and Optimal Flexible Architecture

This chapter describes the concepts of multiple Oracle homes and Optimal Flexible Architecture (OFA) for Oracle8i Personal Edition for Windows 98.

Specific topics discussed are:

• Introduction to Multiple Oracle Homes and OFA

• Multiple Oracle Homes Overview

• Which Products Are Multiple Oracle Home-Enabled?

• Changing the Value of PATH

• Exiting Oracle Universal Installer After Entering Name and PATH

• Setting Variables in the Environment or the Registry

• Optimal Flexible Architecture Overview

• Differences Between Directory Trees by Release

• Directory Tree of a Sample OFA-Compliant Database

• OFA Directory Naming Conventions

• OFA and Multiple Oracle Home Configurations

Introduction to Multiple Oracle Homes and OFA

When you install an Oracle database, you are installing one of the largest applications that your computer can support. Using multiple Oracle homes and OFA provides many advantages when administering large databases. The following advantages are the most important:

• Databases are easier to administer because of the structured organization of directories and files, and the consistent naming used for database files.

• A reduction of performance bottlenecks and improved safeguards against disk failures, because input/output (I/O) can be distributed across a number of disks.

• Software upgrades can be tested in an Oracle home in a separate directory from the Oracle home where your production database is located.

Multiple Oracle Homes Overview

This section provides an overview of multiple Oracle homes. It includes the following topics:

• What Is an Oracle Home?

• Benefits of Using Multiple Oracle Homes

• Multiple Oracle Home Functionality in Different Releases

• One-Listener Support of Multiple Oracle Homes

• Multiple Oracle Home Environments

What Is an Oracle Home?

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

• Location of installed product files (for example, C:\ORACLE\ORA81)

• PATH variable pointing to the products' binary files

• Registry entries

• Program groups

Oracle homes also have a name associated with them, which you specify along with their location during installation.

Benefits of Using 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 a Release 8.x.x database patch before you run your production database Release 8.x.x against it.

Multiple Oracle Home Functionality in Different Releases

Modifications to multiple Oracle home functionality have occurred since it was introduced in Release 8.0.4. This table helps you determine the capabilities of your Oracle home depending on the release you are using.

Release	Oracle Home Functionality
Before 8.0.4	Releases of Oracle for Windows 95 prior to Release 8.0.4 only 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 first or second-digit release numbers. For example, you could install Release 7.2 products and Release 7.3 products and Release 7.x and 8.x 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 of the same Oracle products on the same computer; one installation would overwrite the other.
8.0.4	You can install one or more releases of Oracle products in multiple Oracle homes. For example, with multiple Oracle homes, you can install Releases 8.0.x and 8.1.3 products or 7.x and 8.0.x products in different Oracle homes on the same computer. You can also install different releases of Oracle products in the same Oracle home provided they have different first or second-digit release numbers. For example, you can install Release 7.2 products and Release 8.0.x products in the same Oracle home.
8.1.5 to 8.1.6	Releases 8.1.5 and 8.1.6 have the same multiple Oracle home functionality as Release 8.0.4 and later, but with these restrictions: You cannot install releases 8.1.5 or 8.1.6 into an Oracle home that was created using the old Installer. (The old Installer was called Oracle Installer and was used for pre-8.1.5 installations; the new Java-based Installer is called Oracle Universal Installer.) You cannot install releases of Oracle prior to Release 8.1.5 into an Oracle home that was created by Release 8.1.5 or 8.1.6. Releases 8.1.5 and 8.1.6 must be installed in separate Oracle homes. You cannot have more than one release per Oracle home. In Release 8.1.6 Personal Edition for windows 98, multiple oracle home support for RDBMS has been added.
8.1.5 to 8.1.6	You can use a Release 8.1.6 listener to spawn a connection to a Release 8.1.x, 8.0.x, or 7.3.x database. However, in a mixed environment, you cannot enable the use of shared sockets. Some restrictions exist in using 8.1.6 listeners to spawn connections to earlier versions of the database. These include: You should enable process mode external procedures for Release 8.1.6 if you want to spawn a connection to a Release 8.0.4 databases. You must install the Release 8.0.4.0.3 (or later) patch for Net8. You cannot enable shared sockets.

One-Listener Support of Multiple Oracle Homes

You can use one listener for spawning connections to databases for multiple Oracle homes. You only need to add all the System Identifiers (SIDs) to the SID_LIST section in the ORACLE_BASE\ORACLE_HOME\NETWORK\ADMIN\LISTENER.ORA file.

Because the SID is unique to a system across different Oracle homes, the listener can spawn the database thread for a specific SID in the correct Oracle home, and the ORACLE_HOME parameter (used in UNIX environments only) is not needed in the LISTENER.ORA.

Note: There may be multiple LISTENER.ORA files on your computer, one for each Oracle home. To ensure that you use the correct LISTENER.ORA file, check the Oracle home name in the listener service.

Multiple Oracle Home Environments

This section describes the differences among multiple Oracle home environments since multiple Oracle homes were first introduced in Release 8.0.4.

Release 8.0.4 and later 8.0.x Oracle Home Environments

If you have Release 8.0.4 or later 8.0.x Oracle homes on your computer, note these differences between the first Oracle home you installed and more recent Oracle homes you may install:

Element	First Oracle Home	Each Additional Oracle Home
Program Groups	Oracle for Windows 98 Oracle home name is not appended to the group.	Appends the Oracle home name to the program group. For example: Oracle for Windows 98 - HOME_NAME
Registry Entries	Located in HKEY_LOCAL_MACHINE\SOFTWARE\ORACLE	Subkeys for each Oracle home are 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, "Oracle8i Configuration Parameters and the Registry".
System Identifier (SID) name for starter database	Automatically named ORCL	Having more than one instance of database was not supported on Windows 98 platform.

Release 8.1 Oracle Home Environment

Release 8.1 Oracle homes are slightly different from pre-8.1 Oracle homes.

Element	First Oracle Home	Each Additional Oracle Home
Program Groups	Oracle - HOME_NAME	Oracle - HOME_NAME
Registry Entries	Located in HKEY_LOCAL_MACHINE\SOFTWARE\ORACLE\HOME0	Subkeys for each Oracle home are added in the HKEY_LOCAL_MACHINE\SOFTWARE\ORACLE subkey. For example, the next subkeys after HOME0 are HOME1, HOME2, HOME3, and so on. For more information on the registry keys and subkeys, see Appendix C, "Oracle8i Configuration Parameters and the Registry".
System Identifier (SID)1 name and DB_NAME	For 8.1.5 and 8.1.6, you must type in the global database name and SID name of your choice when prompted during installation.	Having more than one instance of Personal Edition database on Windows 98 platform is supported in Release 8.1.6.

1 For Releases 8.1.5 and 8.1.6, the SID can be a maximum of 64 alphanumeric characters in length. For all releases prior to 8.1.5, the SID was a maximum of 4 alphanumeric characters.

Which Products Are Multiple Oracle Home-Enabled?

You can install all products on the CD-ROM into your first Oracle home on a "clean" computer (that is, there is no other Oracle software on the computer) without any conflict.

If you create more Oracle homes, and install the same products that you installed into the first Oracle home, conflicts can arise that cause your original database to function incorrectly if the products are not multiple Oracle home-enabled (multiple Oracle home products.)

To avoid such problems, check the following product classifications before installing multiple versions of the same product on your computer. Oracle products are classified as follows:

• Products Supporting Multiple Oracle Homes

• Products Supporting a Single Oracle Home

• Products Not Supporting Multiple Oracle Homes

• Products Not Associated with an Oracle Home

Products Supporting Multiple Oracle Homes

You can install multiple Oracle home products multiple times in different Oracle homes. All products are multiple Oracle home products unless they are listed in:

• "Products Supporting a Single Oracle Home" or

• "Products Not Supporting Multiple Oracle Homes"

Products Supporting a Single Oracle Home

You can install single Oracle home products into any Oracle home, but only once per computer. When installing groups of products, if any of the products in the following list are included in the group and already exist on the computer, do not install them a second time:

• Oracle Objects for OLE

• Oracle Open Database Connectivity (ODBC) Driver

• All products that depend on any of these products

Products Not Supporting Multiple Oracle Homes

All Oracle7 products and all Release 8.0.3 products are non multiple Oracle home products. You can only install these products into an old-style Oracle home (pre-8.0.4 Oracle home is an old-style Oracle home).

Products Not Associated with an Oracle Home

Products not associated with an Oracle home have no restrictions into how many Oracle homes you install them. They include the following:

• Oracle Universal Installer

• Java Runtime Environment

When you install these products, Oracle Universal Installer requires that you install them into any Oracle home. However, these files are actually installed in the directory X:\PROGRAM FILES\ORACLE, where X: is the hard drive where Windows 98 is installed.

Changing the Value of PATH

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 is the one in the Oracle home listed first in your path, unless you specifically invoke a different release of the product by one of the following methods:

• Specifying the full directory path name to the release of the product you want to use at the MS-DOS command prompt.

• Changing to the directory that contains the executable you want to use.

• Changing your PATH so that the first entry points to the binary files for the product release you want to use.

You can change the value of PATH by using one of the following methods:

• Using Oracle Home Selector

• At the System Level

  You can assign a new value at the system level. The new value exists until you change the value of PATH again.

• At the MS-DOS Command Prompt

  You can assign a new value at the MS-DOS command prompt. The new value reverts to its previous value when you quit the session.

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.

To change the value of PATH using Oracle Home Selector:

1. Choose Start > Programs > Oracle Installation Products > 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.

3. Click OK.

At the System Level

To change the value of PATH at the system level:

On Windows 98

1. Open the AUTOEXEC.BAT file.

2. Edit the value of the PATH statement.

3. Reboot your computer.

At the MS-DOS Command Prompt

To change the value of PATH at the MS-DOS command prompt:

At the MS-DOS command prompt, enter:

C:\> SET 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 Oracle Home Selector or change the value of PATH at the system level. Both methods are described above.

Exiting Oracle Universal Installer After Entering Name and PATH

If you have to exit Oracle Universal Installer unexpectedly after you have entered the name and path for an Oracle home (for example, because there is no more disk space in the path you specified), you cannot specify a different path until you delete the HOMEID key and the IDx key corresponding to that Oracle home from the registry. To do this:

1. 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.

2. Delete the HOMEID subkey you just located.

3. Delete the appropriate IDx subkey 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.

   See Also: Appendix C, "Oracle8i Configuration Parameters and the Registry" for more information on the registry keys and subkeys.

Setting Variables in the Environment or the Registry

Variables set in the environment always override the value of equivalent variables set in the registry. The following section describes the consequences of setting two of the most commonly-used environment variables, ORACLE_HOME and TNS_ADMIN.

ORACLE_HOME

Oracle Corporation recommends that you never set the ORACLE_HOME environment variable because it is not required for Oracle products to function properly. If you set the ORACLE_HOME environment variable, Oracle Universal Installer will unset it for you. Oracle products find the value of ORACLE_HOME at the location specified by the ORACLE_BASE\ORACLE_HOME\BIN\ORACLE.KEY file. If there is a need to set ORACLE_HOME in the environment for another reason, care must be taken to only run software from that Oracle home when the variable is set.

When you run an Oracle program from the MS-DOS command prompt, the first executable by that name found in the directory path runs. For example, C:\> SQLPLUS. Alternately, if you specify a full directory path, the specified program runs. For example, C:\ORACLE\ORA81> SQLPLUS.

If you modify the value of PATH using any of the three methods described in the previous section, "Using Oracle Home Selector", "At the System Level", or "At the MS-DOS Command Prompt", you can change the choice of which version of a program is run from the MS-DOS command prompt. In sum, modifying the value of PATH indicates from which Oracle home to run executables, at the MS-DOS command prompt, when no full directory path is specified.

Once an Oracle program starts, it looks for all environment variables in the following order:

1. In the current environment

2. In the registry key for the Oracle home from which the program is running.

   The program knows where it's running from by calling Window 98 to obtain the executable's path name, and then parsing the path name to get the directory from which it's running. In the ORACLE_BASE\ORACLE_HOME\BIN directory where the executable resides, there is a file called ORACLE.KEY. This file specifies where in the registry to look for variables when programs from that particular Oracle home are run.

   For example, if you run C:\ORACLE\ORA81\BIN\SQLPLUS.EXE, SQLPLUS.EXE looks in C:\ORACLE\ORA81\BIN\ORACLE.KEY to find out where to look for its registry variables. If the ORACLE.KEY file does not exist (for version 7.x and some version 8.0 Oracle homes), Oracle uses HKEY_LOCAL_MACHINE\SOFTWARE\ORACLE to locate the registry variables.

   In a typical case, there are no Oracle variables (that is, ORACLE_HOME) set in the environment. Any programs run from a Release 8.0.4 Oracle home look in the ORACLE.KEY file in that Oracle home and find their variables (including ORACLE_HOME) in the correct registry key. Likewise for Release 8.1.6, the Oracle home that gets priority depends on the PATH, but regardless of the PATH setting, all the software works correctly.

Consequences of Setting ORACLE_HOME

If you set ORACLE_HOME in the environment, then software run from another Oracle home will not work reliably. The conflict occurs when you set ORACLE_HOME to point to one Oracle home directory, then attempt to run programs from a second Oracle home. These programs first check for any environment variable settings (such as ORACLE_HOME), before checking the registry through the ORACLE.KEY file. Since ORACLE_HOME is set, the programs in the second Oracle home attempt to use files in the first Oracle home, causing a conflict.

For example, assume you have Release 8.0.4 installed in C:\ORAWIN95, and Release 8.1.6 installed in C:\ORACLE\ORA81, and ORACLE_HOME is set to C:\ORAWIN95 in the environment. If you run a program from C:\ORACLE\ORA81\BIN, that program first looks in the environment for all variables before looking at its ORACLE.KEY file. So, a program run from your Release 8.1.6 Oracle home runs with ORACLE_HOME=C:\ORAWIN95. Therefore, anything that the program uses ORACLE_HOME for will be looked for in C:\ORAWIN95, where it may not exist. Examples include message files (.MSB), SQL scripts (.SQL), and any other files opened by the program and based on ORACLE_HOME.

TNS_ADMIN

Oracle software looks for TNS_ADMIN in one location in the registry (depending upon the type of Oracle home installed). If you installed software into the default Oracle home, then any software running from that Oracle home will look in HKEY_LOCAL_MACHINE\SOFTWARE\ORACLE. If you installed a new-style (8.0.4 or later) multiple Oracle home, then the Oracle software looks in HKEY_LOCAL_MACHINE\SOFTWARE\ORACLE\HOMEID. The ALL_HOMES key is used by the installer and plays no role when translating variables.

The environment always overrides the registry, so if TNS_ADMIN is set in the environment, that takes precedence over the TNS_ADMIN setting in the registry. No variables should be set in the environment by the Oracle Home Selector except for the PATH.

Optimal Flexible Architecture Overview

The Oracle Optimal Flexible Architecture (OFA) is a set of file naming and placement guidelines for Oracle software and databases. It can also be thought of as a set of good habits to adopt when organizing Oracle directories and files on your computer. All Oracle products on the CD-ROM are OFA-compliant; that is, Oracle Universal Installer places Oracle products in directory locations that follow the OFA guidelines. Although using OFA is not a requirement, Oracle Corporation recommends that you use it if your database will grow in size, or if you plan to have multiple databases.

The aim of OFA is to prevent an entire class of problems that can occur when you have different versions of Oracle software and multiple, growing databases on your computer. OFA is designed to provide significant benefits in the following areas:

• Ease of maintenance of Oracle software and databases through standard file organization

• Reliability through data spanning multiple physical drives

• Performance through decreased I/O contention for disks

For example, one of the many benefits of OFA is that Oracle Universal Installer separates Oracle software executables from database files. Previously, database files were placed in ORACLE_HOME\DATABASE, a subdirectory of the Oracle home directory that also contained Oracle software. Using OFA, Oracle Universal Installer puts Oracle software in ORACLE_BASE\ORACLE_HOME and database files in ORACLE_BASE\ORADATA.

Putting database files in a subdirectory of the Oracle home directory that also contained Oracle software made upgrades unnecessarily difficult. Separating software from data is essential, because over time, when you upgrade a database to the latest release, the new Oracle software executables will be placed in a different Oracle home directory. After the upgrade is judged to have been successful, you can easily remove the old Oracle home directory and reclaim space because the database does not reside there.

Benefits of an OFA-Compliant Database

An OFA-compliant database has the following benefits:

• Easier database administration and management of database growth

  The file system is organized to simplify the following tasks:

  • Locating specific database files

  • Adding database files as the database grows

• Fewer performance bottlenecks

  Disk contention decreases, because Oracle administration files, binary files, and data files that used to be on one disk can now reside in separate directories or in separate directories on separate disks.

• Safeguards against disk failures

  By spreading files across more than one disk, disk failures impact as little data as possible.

• Support for concurrent execution of application software

  You can run multiple versions of application software simultaneously, enabling you to test and use a new release of an application before abandoning the previous version. Transferring to a new version after an upgrade is simple for the database administrator and transparent for the user.

Characteristics of an OFA-Compliant Database

An OFA-compliant database has the following characteristics:

• Independent subdirectories

  Categories of files are separated into independent subdirectories so that files in one category are minimally affected by operations on files in other categories.

• Consistent naming conventions for database files

  Database files are named to realize the following advantages:

  • Database files are easily distinguishable from all other files

  • Files of one database are easily distinguishable from files of another database

  • Control files, redo log files, and data files are easily identifiable

  • Clearly indicated association of data files to tablespaces

• Integrity of Oracle home directories

  You can add, move, or delete Oracle home directories without having to revise programs that refer to them.

• Distinguishes administrative information for each database

  The ability to separate administrative information about one database from that of another ensures a reasonable structure for the organization and storage of administrative data.

• Separation of tablespace contents

  Tablespace contents are separated to realize the following advantages:

  • Minimize tablespace-free space fragmentation

  • Minimize I/O request contention

  • Maximize administrative flexibility

• Tuning I/O loads across all disks

  I/O loads are tuned across all disks, including disks storing Oracle data in raw devices, if needed.

Differences Between Directory Trees by Release

OFA has necessitated changes to the Oracle database directory tree. This table lists the differences:

Element	Pre-8.1.5 non-OFA-Compliant	Post-8.1.5 OFA-Compliant
Name of the top-level directory where Oracle is installed.	When you install Oracle8i Personal Edition all subdirectories are located under a top-level ORACLE_HOME directory that by default is C:\ORAWIN95. See the following figure for a depiction of the pre-8.1.5 non-OFA-compliant directory tree.	When you install Oracle8i Personal Edition all subdirectories are no longer under a top-level ORACLE_HOME directory. There is now a new top-level directory called ORACLE_BASE that is of the form X:\ORACLE where X is any hard drive. If you install an OFA-compliant database using Oracle Universal Installer defaults, ORACLE_BASE is C:\ORACLE. \ORACLE_HOME directories are located under ORACLE_BASE. The \ORADATA and \ADMIN directories, which contain the database files and database administration files, are also located under ORACLE_BASE. See the following figure for a depiction of the 8.1.5 and 8.1.6 OFA-compliant directory tree.
Database file names	Database files have the SID in the database file name. For example, the first control file is named CTL1SID.ORA.	Database files no longer have the SID in the database file name. For example, the first control file is named CONTROL01.CTL. There is no need for the presence of the SID in the file name because all the database files for a particular database are placed in \ORADATA under a directory called DB_NAME that is named for that database.
Database file name extensions	All database files have the same .ORA extension.	The convention of having .ORA as the file name extension for database files is no longer used. Database file names now have more meaningful extensions. These are .CTL for control files, .LOG for log files, and .DBF for data files.

The following figure provides a top-level overview of the old and new database directory trees:

Pre-8.1.5 non-OFA-Compliant Oracle on Windows 98 Directory Tree

8.1.6 OFA-Compliant Oracle on Windows 98 Directory Tree

Directory Tree of a Sample OFA-Compliant Database

The following is the complete hierarchical directory tree of a sample OFA-compliant database:

X:\ORACLE_BASE				C:\ORACLE is the default ORACLE_BASE directory
	\ORACLE_HOME1			\ORA81 is the name of the first Oracle home by default
		\BIN		Subtree for Oracle binaries
		\NETWORK		Subtree for Net8
		\ASSISTANTS		Configuration assistants
	\ORADATA			Subtree for Oracle database files
		\DB_NAME1		Subtree for DB_NAME1 database files
			CONTROL01.CTL	Control file 1
			CONTROL02.CTL	Control file 2
			CONTROL03.CTL	Control file 3
			DRO1.DBF	interMedia related objects
			SYSTEM01.DBF	System tablespace data file
			RBS01.DBF	Rollback tablespace data file
			INDX01.DBF	Index tablespace data file
			TEMP01.DBF	Temporary tablespace data file
			USERS01.DBF	Users tablespace data file
			REDO01.LOG	Redo log file group 1, member 1
			REDO02.LOG	Redo log file group 2, member 1
			REDO03.LOG	Redo log file group 3, member 1
		\DB_NAME2		Subtree for DB_NAME2 database files
			CTL DBF LOG	Control, data, and redo log files
		\DB_NAME3		Subtree for DB_NAME3 database files
			CTL DBF LOG	Control, data, and redo log files
	\ADMIN			Subtree for database administration files
		\DB_NAME1		Subtree for DB_NAME1 database administration files
			\ADHOC	Ad hoc SQL scripts
			\ADUMP	Audit files
			\ARCH	Archived redo log files
			\BDUMP	Background process trace files
			\CDUMP	Core dump files
			\CREATE	Database creation files
			\EXP	Database export files
			\PFILE	Initialization parameter file
			\UDUMP	User SQL trace files
		\DB_NAME2		Subtree for DB_NAME2 database administration files
			. . .
		\DB_NAME3		Subtree for DB_NAME3 database administration files
			. . .
	\ORACLE_HOME2			Second Oracle home
		\ . . .
	\ORACLE_HOME3			Third Oracle home
		\ . . .

OFA Directory Naming Conventions

OFA uses directory naming conventions that make it easy to identify the precise Oracle home and database name that is associated with a set of files. This section describes the naming conventions used for the top-level directories of an OFA-compliant database directory tree:

• ORACLE_BASE Directory

• ORACLE_HOME Directory

• ADMIN Directory

• ORADATA Directory

• DB_NAME Directory

ORACLE_BASE Directory

ORACLE_BASE is the root of the Oracle directory tree. If you install an OFA-compliant database using Oracle Universal Installer defaults, ORACLE_BASE is X:\ORACLE where X is any hard drive. For example, C:\ORACLE.

If you are installing Oracle8i Personal Edition for Windows 98 on a clean computer, you may want to change ORACLE_BASE to an appropriate value before running Oracle Universal Installer. Most users will not need or want to do this.

Before you run Oracle Universal Installer for the first time, change the value of ORACLE_BASE at the system level. Only change the value of ORACLE_BASE before you run Oracle Universal Installer for the first time because if there is an existing ORACLE_BASE, and you change it, there will be a conflict of Oracle base directories. If you create another ORACLE_BASE when the original ORACLE_BASE already exists, certain tools and the database will not be able to find previously created files because they will look for them in the new ORACLE_BASE instead of the original ORACLE_BASE.

To change the value of ORACLE_BASE at the system level:

Windows 98:

1. Open the AUTOEXEC.BAT file, using a text editor.

2. Edit the value of the ORACLE_BASE statement.

3. Reboot your computer.

   Note: An ORACLE_BASE registry key exists for every Oracle home. Ideally, the value of the ORACLE_BASE registry key will be identical for each Oracle home.

ORACLE_HOME Directory

\ORACLE_HOME is located beneath X:\ORACLE_BASE and contains subdirectories for Oracle software executables and network files.

If you install Oracle8i Personal Edition for Windows 98 on a clean computer and use the default settings, the first Oracle home directory that you create is called \ORA81.

ADMIN Directory

Database administration files are stored in subdirectories of ORACLE_BASE \ADMIN\DB_NAME.

The following table describes the subdirectories for database administration files:

Subdirectories of \ADMIN\DB_NAME	Contain...
\ADHOC	Ad hoc SQL scripts for a given database
\BDUMP	Background process trace files
\CDUMP	Core dump files
\CREATE	Database creation files
\EXP	Database export files
\PFILE	Initialization parameter files
\UDUMP	User process trace files

ORADATA Directory

Database files are stored in ORACLE_BASE\ORADATA\DB_NAME.

The following table describes the database files:

Files in \ORADATA\DB_NAME	Description
CONTROL01.CTL	Control file 1
CONTROL02.CTL	Control file 2
CONTROL03.CTL	Control file 3
SYSTEM01.DBF	SYSTEM tablespace data file
RBS01.DBF	RBS tablespace data file
INDX01.DBF	INDX tablespace data file
TEMP01.DBF	TEMP tablespace data file
USERS01.DBF	USERS tablespace data file
REDO01.LOG	Redo log file group one, member one
REDO02.LOG	Redo log file group two, member one
REDO03.LOG	Redo log file group three, member one

DB_NAME Directory

DB_NAME is the unique name for a particular database and has the same value as the DB_NAME parameter in the initialization parameter file. When you create a database, DB_NAME can be no more than eight characters long and can contain only the following characters:

• Alphabetic characters

• Numbers

• Underscores (_)

• Pound sign (#)

• Dollar sign ($)

OFA and Multiple Oracle Home Configurations

The following sections describe various OFA and multiple Oracle home configurations.

Specifying an ORACLE_HOME Directory

To install an OFA-compliant database, you must specify an Oracle home directory in the Path: field of Oracle Universal Installer of the form:

X:\[PATHNAME]\ORACLE\HOME_NAME

where:

X:\	is any hard drive. For example, C:\.
[PATHNAME]	is an optional directory pathname.
\ORACLE	is a mandatory directory pathname unless you have changed the value of the ORACLE_BASE registry key before performing the installation. See "ORACLE_BASE Directory" for information on how to change the ORACLE_BASE from the default value ORACLE.
HOME_NAME	is the name of the Oracle home.

The following are examples of OFA-compliant Oracle home directories:

• C:\TEST\ORACLE\ORA81

• D:\ORACLE\ORA81

Default OFA Database

To install a default OFA database:

1. Install Oracle8i Personal Edition for Windows 98 Release 8.1.6 on a clean computer (one with no other Oracle software on the computer), and accept the default Oracle Universal Installer settings for the first Oracle home (C:\ORACLE\ORA81) in the Path: field.

2. Complete the installation.

3. Run Oracle Universal Installer again and the same release a second time or Release 8.2.x (when it is available). Accept the default Oracle Universal Installer settings for the first Oracle home (C:\ORACLE\ORA82) in the Path: field.

The default OFA database settings are as follows:

Setting	Value
ORACLE_BASE	is C:\ORACLE and is the same for all Oracle homes
Oracle home 1	is C:\ORACLE\ORA81
Oracle home 2	is C:\ORACLE\ORA82

This figure below illustrates the directory tree:

Non-Default OFA Database, Case 1

To install a non-default OFA database, case 1:

1. Install Oracle8i Personal Edition for Windows 98 Release 8.1.6 and change the default Oracle Universal Installer settings for the first Oracle home from C:\ORACLE\ORA81 in the Path: field to X:\XYZ.

2. Complete the installation.

3. Run Oracle Universal Installer again and change the default Oracle Universal Installer settings for the second Oracle home from C:\ORACLE\ORA82 in the Path: field to Y:\ABC.

For case 1, the non-default OFA database settings are as follows:

Setting	Value
ORACLE_BASE	is X:\XYZ for the first Oracle home and is Y:\ABC for the second Oracle home
Oracle home 1	is X:\XYZ
Oracle home 2	is Y:\ABC

This figure illustrates the resulting directory trees:

Non-Default OFA Database, Case 2

To install a non-default OFA database, case 2:

1. Install Oracle8i Personal Edition for Windows 98 Release 8.1.6 and change the default Oracle Universal Installer settings for the first Oracle home from C:\ORACLE\ORA81 in the Path: field to X:\XYZ\ORACLE\ABC.

2. Complete the installation.

3. Run Oracle Universal Installer again and change the default Oracle Universal Installer settings for the second Oracle home from C:\ORACLE\ORA82 to X:\PQR.

For case 2, the non-default OFA database settings are as follows:

Setting	Value
ORACLE_BASE	is X:\XYZ\ORACLE and is the same for both Oracle homes
Oracle home 1	is X:\XYZ\ORACLE\ABC
Oracle home 2	is X:\PQR

This figure illustrates the resulting directory tree: