B Optimal Flexible Architecture

B.1.1 Advantages of Multiple Oracle Homes and OFA

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

• Structured organization of directories and files, and consistent naming for database files simplify database administration.

• Distribution of I/O across multiple disks prevents performance bottlenecks caused by multiple read or write commands issued simultaneously to a single drive.

• Distribution of applications across multiple disks safeguards against database failures.

• Login home directories are not at risk when database administrators add, move, or delete Oracle home directories.

• Multiple databases, of different versions, owned by different users can coexist concurrently.

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

B.3.1 Top-Level Oracle Directory

In an Oracle8i Release 8.1.3 or earlier release, all subdirectories are located under a top-level ORACLE_HOME directory that by default is c:\orant.

When you install Oracle Database Optimal Flexible Architecture-compliant database, all subdirectories are no longer under a top-level ORACLE_HOME directory. There is a new top-level Oracle base directory, DRIVE_LETTER:\app\username, where DRIVE_LETTER is any hard drive.

The Oracle base directory contains \ORACLE_HOME directories, \oradata directories (for database files), \diag (for diagnostic data), \flash_recovery_area (for recovery operations), and \admin directories (for database administration files).

B.3.2 Database File Names

In Oracle8i Release 8.1.3 and earlier releases, database files have the SID in the database file name. For example, the first control file is named ctl1SID.ora.

Beginning with Oracle8i Release 8.1.4, 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_UNIQUE_NAME that is named for that database.

B.3.3 Database File Name Extensions

In Oracle8i Release 8.1.3 and earlier releases, all database files have the same .ORA extension.

In an Optimal Flexible Architecture-compliant release, the convention of having .ora as the filename extension for database files is no longer used. Database filenames now have more meaningful extensions. These are:

• .ctl for control files

• .log for log files

• .dbf for data files

B.4.1 ORACLE_BASE Directory

ORACLE_BASE is the root of the Oracle directory tree. If you install an Optimal Flexible Architecture-compliant database using Oracle Universal Installer default settings, then ORACLE_BASE is DRIVE_LETTER:\app\username.

If you are installing Oracle Database for Microsoft Windows on a computer with no other Oracle software installed, then you can change the ORACLE_BASE directory before running Oracle Universal Installer. Most users do not need or want to do this.

Do not change the value of ORACLE_BASE after you run Oracle Universal Installer for the first time. If there is an existing ORACLE_BASE and you change it, then there is a conflict of Oracle base directories. If you create another ORACLE_BASE when the original ORACLE_BASE exists, then certain tools and the database are not able to find previously created files. They look for them in the new ORACLE_BASE instead of the original ORACLE_BASE.

B.4.2 ORACLE_HOME Directory

The ORACLE_HOME directory is located under DRIVE_LETTER:\ORACLE_BASE, where DRIVE_LETTER:\is any hard drive, and contains subdirectories for Oracle software executables and network files.

If you install Oracle Database for Windows on a computer with no other Oracle software installed and you use default settings, then the first directory that you create is called \dbhome_1.

B.4.3 ADMIN Directory

Database administration files are stored in subdirectories of ORACLE_BASE \admin\DB_UNIQUE_NAME.

Automatic Diagnostic Repository (ADR) directories replace the bdump, cdump, and udump directories for the database. The ADR diagnostic data goes into the ORACLE_BASE\diag\rdbms\DB_UNIQUE_NAME\instance_name

Some of these subdirectories are:

\alert
\hm
\incident
\incpkg
\ir
\lck
\metadata
\stage
\sweep
\trace

B.4.4 ORADATA Directory

Database files are stored in ORACLE_BASE\oradata\DB_UNIQUE_NAME. Names and brief descriptions of these files are:

CONTROL01.CTL    --control file 1
CONTROL02.CTL    --control file 2
CONTROL03.CTL    --control file 3
EXAMPLE01.DBF    --EXAMPLE tablespace data files
SYSAUX01.DBF     --SYSAUX tablespace data files
SYSTEM01.DBF     --SYSTEM tablespace data file
TEMP01.DBF       --TEMP tablespace data file
USERS01.DBF      --USERS tablespace data file
*.dbf            --data files corresponding to each tablespace in your database
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

B.4.5 RECOVERY_AREA Directory

The recovery_area directory stores and manages files related to backup and recovery. It contains a subdirectory for each database on the system. A fast recovery area is an optional disk location that you can use to store recovery-related files such as control files and online redo log copies, archived logs, flashback logs, and Oracle Database Recovery Manager (RMAN) backups. Oracle and RMAN manage the files in the fast recovery area automatically.

B.5.1 Specifying an ORACLE_HOME Directory

To install an Optimal Flexible Architecture-compliant database, you must specify an Oracle home directory in the form of:

DRIVE_LETTER:\app\username\product\11.2.0\dbhome_1 

where:

• DRIVE_LETTER:\ is any hard drive. For example, c:\

• \app\username is the ORACLE_BASE before performing the installation.

• dbhome_1 is the default directory name.

The following are examples of Optimal Flexible Architecture-compliant Oracle home directories:

• c:\app\test1\product\11.2.0\dbhome_1

• d:\app\test2\product\11.2.0\dbhome_1

B.5.2 Installing a Default Optimal Flexible Architecture Database: Example 1

This example shows how to create all Oracle homes within one Oracle base directory.

1. Install any Oracle Database that supports Optimal Flexible Architecture (Oracle Database Release 8.1.6 or later) on a computer with no other Oracle software installed and ensure that you accept the default settings for the Oracle home (for example, c:\app\username\product\11.2.0\dbhome_1).

2. Install any Oracle Database in a second Oracle home accepting the default settings.

Table B-1 shows the default Optimal Flexible Architecture database settings.

B.5.3 Installing a Nondefault Optimal Flexible Architecture Database: Example 2

In this example, you install each Oracle home into its own directory, but they all share the same Oracle base.

1. Install any Oracle Database that supports Optimal Flexible Architecture (Oracle Database 8.1.6 or later) on a computer with no other Oracle software installed and change the default Oracle Universal Installer settings for the first Oracle home (for example, from c:\oracle\ora81 to X:\xyz\oracle\abc).

2. Install any Oracle Database and change the default Oracle Universal Installer settings for the second Oracle home (for example, from c:\oracle\ora10 to X:\pqr).

Table B-2 shows the nondefault Optimal Flexible Architecture database settings for this example.

The resulting directory tree would look similar to this:

X:\pqr                         --Oracle home 2
  \bin
  \network
X:\xyz
    \oracle                    --ORACLE_BASE for both Oracle homes
      \abc                     --Oracle home 1
        \bin
        \network
      \admin
        \DB_UNIQUE_NAME1
          \dpdump
          \
        \DB_UNIQUE_NAME2
          \...
      \oradata
        \DB_UNIQUE_NAME1
          CONTROL01.CTL
          CONTROL02.CTL
          CONTROL03.CTL
          EXAMPLE01.DBF
          SYSAUX01.DBF
          SYSTEM01.DBF
          TEMP01.DBF
          USERS01.DBF
          REDO01.LOG
          REDO02.LOG
          REDO03.LOG
        \DB_UNIQUE_NAME2

B.6.1 Directory Naming

Top-level names of the Optimal Flexible Architecture directory tree differ between Windows and UNIX. However, main subdirectory names and file names are the same on both operating systems.

B.6.2 ORACLE_BASE Directory

On Windows, Oracle base is associated with an Oracle home directory. ORACLE_BASE is defined in the registry (for example, in HKEY_LOCAL_MACHINE\SOFTWARE\ORACLE\KEY_HOME_NAME).

On UNIX, ORACLE_BASE is associated with a UNIX user's environment.

B.6.3 Support for Symbolic Links on Windows

The goal of Optimal Flexible Architecture is to place all Oracle software under one ORACLE_BASE directory and to spread files across different physical drives as your databases increase in size.

On UNIX, although everything seems to be in one directory on the same hard drive, files can be on different hard drives if they are symbolically linked or have that directory as a mount point.

On Windows, you can use volume mount points to mount files on different hard drives to a single directory. You may have oradata directories on multiple drives, with data files in each one, on Windows version which does not support volume mount points.

Oracle recommends that you use one logical drive to store your database administration files and that you place other files, as needed, on other logical drives in an oradata\DB_UNIQUE_NAME directory.

In the following example, there are four logical drives for a database named prod:

• c:\ contains an Oracle home and database administration files.

• f:\ contains redo log files. The F:\ drive could also represent two physical drives that have been striped to increase performance.

• g:\ contains one of the control files and all tablespace files. The G:\ drive could also use a RAID Level-5 configuration to increase reliability.

• h:\ contains the second control file.

The directory structure would look similar to this:

c:\app\username\product\11.2.0   --First logical drive
    \dbhome_1                  --Oracle home
      \bin                 --Subtree for Oracle binaries
      \network             --Subtree for Oracle Net
      \...
    \admin                 --Subtree for database administration files
      \prod                --Subtree for prod database administration files
        \adump             --Audit files
        \dpdump                      --Default directory for data pump operations.
        \pfile             --Initialization parameter file

f:\app\username\product\11.2.0   --Second logical drive (two physical drives, striped)
    \oradata               --Subtree for Oracle Database files
      \prod                --Subtree for prod database files
        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

g:\app\username\product\11.1.0   --Third logical drive (RAID level 5 configuration)
    \oradata               --Subtree for Oracle Database files
      \prod                --Subtree for prod database files
        CONTROL01.CTL      --Control file 1
        EXAMPLE01.DBF      --EXAMPLE tablespace data files
        SYSAUX01.DBF       --SYSAUX tablespace data files
        SYSTEM01.DBF       --System tablespace data file
        TEMP01.DBF         --Temporary tablespace data file
        USERS01.DBF        --Users tablespace data file

h:\app\username\product\11.2.0   --Fourth logical drive
    \oradata               --Subtree for Oracle Database files
      \prod                --Subtree for prod database files
        CONTROL02.CTL      --Control file 2