This appendix describes the Optimal Flexible Architecture (OFA) standard:
Changes to the Optimal Flexible Architecture for Oracle Database 10g
Optimal Flexible Architecture and Multiple Oracle Home Configurations
Comparison Between Optimal Flexible Architecture on Windows and UNIX
The Optimal Flexible Architecture standard is a set of file naming and configuration guidelines created to ensure reliable Oracle installations that require little maintenance.
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 Optimal Flexible Architecture standard 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, which are often vulnerable to data corruption
Facilitate 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
You can think of Optimal Flexible Architecture as a set of good habits to adopt when organizing Oracle directories and files on your computer. All Oracle components on the installation media are Optimal Flexible Architecture-compliant; that is, Oracle Universal Installer places Oracle components in directory locations that follow Optimal Flexible Architecture guidelines. Although using Optimal Flexible Architecture is not a requirement, Oracle recommends that you use it if your database will grow in size, or if you plan to have multiple databases.
The goal of Optimal Flexible Architecture is to prevent an entire class of problems that can occur when you have different releases of Oracle software and multiple, growing databases on your computer.
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 Optimal Flexible Architecture, Oracle Universal Installer puts Oracle software in ORACLE_BASE
\
ORACLE_HOME
and database files in ORACLE_BASE
\oradata
. When you upgrade a database to the latest release, the new Oracle software executables will be placed in a different Oracle home directory. After you judge the upgrade as successful, you can remove the old Oracle home directory and reclaim space, because the database does not reside there.
An Optimal Flexible Architecture-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 easily distinguishable from all other files. Files of one database are easily distinguishable from files of another database. Data files, redo log files, and control files are easily identifiable. Data f iles are clearly associated with a particular tablespace.
Integrity of Oracle home directories
You can add, move, or delete Oracle home directories without having to revise applications that refer to them.
Separation of administrative information for each database
The ability to distinguish 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 free space fragmentation and I/O request contention are minimized, while administrative flexibility is maximized.
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.
For previous releases of Oracle Database, the Optimal Flexible Architecture recommended Oracle home path was similar to the following:
c:\> oracle\ora92
In Oracle Database 10g release 1 (10.1), the Optimal Flexible Architecture recommended Oracle home path changed. The Optimal Flexible Architecture recommended path is now similar to the following:
c:\> oracle\product\10.2.0\type_n
In this example, type
is the type of Oracle home, for example Oracle Database (database
) or Oracle Database Client (client
), and n
is an optional counter. This syntax provides the following benefits:
You can install different products with the same release number in the same Oracle base directory, for example:
c:\> oracle\product\10.2.0\db_1 c:\> oracle\product\10.2.0\client_1
You can install the same product more than once in the same Oracle base directory, for example:
c:\> oracle\product\10.2.0\db_1 c:\> oracle\product\10.2.0\db_2
Optimal Flexible Architecture has necessitated changes to the Oracle Database directory tree. This section lists the differences:
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 an Oracle8i release 8.1.4 or later Optimal Flexible Architecture-compliant database, all subdirectories are no longer under a top-level ORACLE_HOME
directory. There is now a new top-level Oracle base directory of the form DRIVE_LETTER
:\oracle\product\10.2.0
, where DRIVE_LETTER
is any hard drive.
The Oracle base directory contains \
ORACLE_HOME
directories, \oradata
directories (for database files), \flash_recovery_area
(for recovery operations), and \admin
directories (for database administration files).
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 ctl1
SID
.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_NAME
that is named for that database.
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
Optimal Flexible Architecture 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 top-level directories of an Optimal Flexible Architecture-compliant database directory tree:
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 SYSTEM_DRIVE
:\oracle\product\10.2.0
.
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 will 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 will be a conflict of Oracle base directories. If you create another ORACLE_BASE
when the original ORACLE_BASE
already exists, then certain tools and the database will not be able to find previously created files. They will look for them in the new ORACLE_BASE
instead of the original ORACLE_BASE
.
See Also:
Your operating system documentation for instructions about editing environment variablesThe \ORACLE_HOME
directory is located under SYSTEM_DRIVE:\ORACLE_BASE
, where 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 Oracle home directory that you create is called \db_1
.
Database administration files are stored in subdirectories of ORACLE_BASE
\ \admin\
DB_NAME
. Names and brief descriptions of some of these subdirectories are:
\bdump --background process trace files \cdump --core dump files \create --database creation files \exp --database export files \pfile --initialization parameter files \udump --user SQL trace files
Database files are stored in ORACLE_BASE
\oradata\
DB_NAME
. Names and brief descriptions of these files are:
CONTROL01.CTL --control file 1 CONTROL02.CTL --control file 2 CONTROL02.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
Note:
This directory structure allows for disk striping only on UNIX platforms. See "Support for Symbolic Links on Windows".The flash_recovery_area
directory stores and manages files related to backup and recovery. It contains a subdirectory for each database on the system. A flash 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 flash recovery area automatically.
See Also:
Oracle Database Backup and Recovery Basics to learn how to create and use a flash recovery areaThe following sections describe various Optimal Flexible Architecture and multiple Oracle homes configurations.
To install an Optimal Flexible Architecture-compliant database, you must specify an Oracle home directory in the Path field of Oracle Universal Installer. It is of the form:
SYSTEM_DRIVE:\[PATHNAME]\oracle\product\10.2.0\ORACLE_HOME
where:
SYSTEM_DRIVE:\
is any hard drive. For example, c:\
PATHNAME
is an optional directory path name.
\oracle
is a mandatory directory path name, unless you changed the value of registry key ORACLE_BASE
before performing the installation.
ORACLE_HOME
is the name of the Oracle home.
The following are examples of Optimal Flexible Architecture-compliant Oracle home directories:
c:\test\oracle\product\10.2.0\db_1
d:\oracle\product\10.2.0\db_1
This example shows how to create all Oracle homes within one Oracle base directory.
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 make sure that you accept the default settings for the Oracle home (for example, c:\oracle\ora81
).
Install any Oracle Database in a second Oracle home accepting the default settings.
Table C-1 shows the default Optimal Flexible Architecture database settings.
In this example, you install Oracle Database so that each Oracle home has its own Oracle base.
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
).
Install any Oracle Database (for example, Oracle Database 10g release 1 (10.2)) in a second Oracle home and change the default Oracle Universal Installer settings for the second Oracle home (for example, from X:\xyz
to Y:\abc
).
Table C-2 shows the nondefault Optimal Flexible Architecture database settings for example 1.
Table C-2 Nondefault Optimal Flexible Architecture Database Settings: Example 1
Directory | Value |
---|---|
|
|
Oracle home 1 |
|
Oracle home 2 |
|
The resulting directory tree would look similar to this:
X:\xyz -- Oracle home 1 \admin \DB_NAME1 \DB_NAME2 \bin \network \oradata \DB_NAME1 CONTROL01.CTL CONTROL02.CTL CONTROL03.CTL EXAMPLE01.DBF SYSAUX01.DBF SYSTEM01.DBF TEMP01.DBF USERS01.DBF REDO01.LOG REDO02.LOG REDO03.LOG \DB_NAME2 Y:\abc -- Oracle home 2 \admin \DB_NAME1 \DB_NAME2 \bin \network \oradata \DB_NAME1 CONTROL01.CTL CONTROL02.CTL CONTROL03.CTL EXAMPLE01.DBF SYSAUX01.DBF SYSTEM01.DBF TEMP01.DBF USERS01.DBF REDO01.LOG REDO02.LOG REDO03.LOG \DB_NAME2
In this example, you install each Oracle home into its own directory, but they all share the same Oracle base.
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
).
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 C-3 shows the nondefault Optimal Flexible Architecture database settings for this example.
Table C-3 Nondefault Optimal Flexible Architecture Database Settings: Example 2
Setting | Value |
---|---|
|
(same for both Oracle homes) |
Oracle home 1 |
|
Oracle home 2 |
|
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_NAME1 \adhoc \bdump \cdump \create \exp \pfile \udump \DB_NAME2 \... \oradata \DB_NAME1 CONTROL01.CTL CONTROL02.CTL CONTROL03.CTL EXAMPLE01.DBF SYSAUX01.DBF SYSTEM01.DBF TEMP01.DBF USERS01.DBF REDO01.LOG REDO02.LOG REDO03.LOG \DB_NAME2
One of the goals of Optimal Flexible Architecture is to increase reliability and performance by distributing I/O loads across different physical drives. Two ways to do that are:
You can separate and treat Oracle Database log files and database files with different levels of hardware reliability. Oracle Database log files are highly reliable because they are stored redundantly. Creating similar reliability for database files may require you to duplicate all of your data, using disk mirrors.
Disk mirroring usually involves two or more identical drives and either a hardware controller or Windows Disk Administrator. If one disk fails, then the other disks can recover data that would otherwise be lost. Using one of the disks to recover lost data may involve "breaking" the mirror. When the mirror breaks, you must build a new mirror.
Disk mirroring is part of some levels of Redundant Array of Independent Disks (RAID) configurations, provided by the disk controller. The RAID level determines the amount of redundancy. Some RAID levels can use the "hot swapping" feature, which means that you can replace a bad disk with a good one without turning off the computer or losing functionality.
How you set up disks for use in a database depends on the number of disks and the type of hard disk controllers available. If the hard disk controllers support both striping and mirroring, then Oracle recommends you configure the controllers to support striping.
You can configure some controllers at system startup time by issuing a keyboard sequence that brings up configuration programs written by the controller manufacturer. One goal is to stripe as many drives together as possible by configuring the controllers. Each stripe shows up as one logical device.
Striping provides significant performance advantages. All the space from the striped drives appears as a single logical drive. Furthermore, the space is used by interlacing "stripes" of space from all of the disks in the stripe. This means that a large file uses some space from the first disk, then some from the second disk and so on to the last disk, and then starting back at the first disk again. Each file can be spread over all of the striped disks. Multiple CPUs can access data randomly in such a file without contention.
Controllers that support striping usually provide caching as well. This means that data can be written to the controller, and cached and saved for a time in storage not on the disk. Data that is read can be cached on the controller in a similar fashion. Read caching should not be used with Oracle Database, because all database reads are cached already in the System Global Area (SGA). The value of parameter DB_CACHE_SIZE
in the initialization parameter file (init.ora
) determines the buffer size that can be used in the SGA. This value also configures Oracle Database on startup.
Note:
Read caching should be disabled.
Disk write caching should be disabled on disks containing Oracle data files and redo log files where the contents of the write cache are not flushed to disk on power failures or operating system failure. Consult your vendor documentation for additional information.
A raw partition is a portion of a physical disk that is accessed at the lowest possible level. I/O of a raw partition improves performance by approximately 5 percent to 10 percent compared to I/O of a partition containing a file system. Therefore, Oracle encourages you to use raw partitions for your tablespace files.
You implement Optimal Flexible Architecture on Windows and UNIX in the same way. However, differences exist with regard to the following:
Support for Symbolic Links on Windows
See Also:
Your UNIX operating system-specific administrator's reference for information about Optimal Flexible Architecture on UNIXTop-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.
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.
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.
Windows currently does not support symbolic links, so data files will not show up under a single directory as with UNIX. Instead, you may have oradata
directories on multiple drives, with data files in each one. This way, you get Optimal Flexible Architecture benefits, even though data files are not all visible in a single directory.
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_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:\oracle\product\10.2.0 --First logical drive \db_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 \adhoc --Ad hoc SQL scripts \adump --Audit 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 f:\oracle\product\10.2.0 --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:\oracle\product\10.2.0 --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:\oracle\product\10.2.0 --Fourth logical drive \oradata --Subtree for Oracle Database files \prod --Subtree for prod database files CONTROL02.CTL --Control file 2