【标准】Oracle Optimal Flexible Architecture(OFA)简介

关于OFA（Optimal Flexible Architecture）标准的介绍

本文来源于Oracle官网关于OFA的解读，地址如下：

http://docs.oracle.com/cd/E11882_01/install.112/e24321/appendix_ofa.htm#i633068

1.Overview of the Optimal Flexible Architecture Standard

Oracle Documents:

The Optimal Flexible Architecture standard helps you to organize database software and configure databases to allow multiple databases, of different versions, owned by different users to coexist. Optimal Flexible Architecture assists in identification of ORACLE_BASE with its Automatic Diagnostic Repository (ADR) diagnostic data to properly collect incidents.

OFA 标准架构帮助我们组织Oracle 软件，配置数据库。通过OFA架构，我们可以安装多个数据库，这些数据库可以使用不同的版本，不同的用户。Oracle的OFA架构可以帮助数据库自动诊断知识库（ADR）识别ORACLE_BASE目录，并妥善的帮助收集诊断事件的数据。

Oracle Documents 写道

All Oraclecomponents on the installation media are compliant with Optimal Flexible Architecture. Oracle Universal Installer places Oracle Database components in directory locations, assigning the default permissions that follow Optimal Flexible Architecture guidelines.

Oracle安装介质中的所有数据库组件都与OFA标准相兼容。OUI将会把将要安装的数据库组件放置到OFA指定的固定的目录，并且分配相应默认的权限。

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Oracle recommends that you use Optimal Flexible Architecture, especially if the database is huge, or if you plan to have multiple databases.

Oracle公司官方建议我们使用OFA的标准目录结构，尤其是我们的数据库非常的庞大或者我们打算在同一目录下安装多数据库的时候。

2.Advantages of Multiple Oracle Homes and OFA

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

当我们安装管理的数据库将会很大时，使用OFA的多ORACLE_HOMS机制将会十分有用。

Oracle Documents 写道

（1）Structured organization of directories and files, and consistent naming for database files simplify database administration.

（2）Distribution of I/O across multiple disks prevents performance bottle necks caused by multiple read or write commands issued simultaneously（同时）to a single drive.

（3）Distribution of applications across multiple disks safeguards against database failures.

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

（5）Multiple databases, of different versions, owned by different users can coexist concurrently.

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

3.Implementing Optimal Flexible Architecture

3.1 File Systems

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The following sections describe the conventions（公约） for mount points:

Numberof File Systems

NamingConventions

3.1.1 Number of FileSystems

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To fully implement the Optimal Flexible Architecture recommendations for a database stored on file systems that are not striped or mirrored, you require at least three file systems located on separate physical devices.

为了完全实现OFA架构，在没有实现基础存储条带化和镜像的数据库环境中，Oracle建议将数据库存储在文件系统上，并且需要3个独立的物理设备。

3.1.2 Naming Conventions（命名约定）

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Name all filesystem mount points using the syntax /pm, where p is a string constant（常数） and m is a unique fixed-length key (typically a two-digit number) used to distinguish each mount point. Forexample: /u01 and/u02, or /disk01 and /disk02.

文件系统的名字需要挂载到/pm目录下，这里的p代表一个字符串常量，m 代表一个定长的值，这个值通常由2个数字组成。如：/u01,u02 或者 /disk01,/disk02。

3.2 Naming Directories(OFA的命名目录）

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The following sections describe the naming conventions for directories that are compliant with the Optimal Flexible Architecture standard:

（1）OracleBase Directory Naming Convention
（2）NamingMount Points for Very Large Databases (VLDBs)
（3）Referring to Path Names
（4）OracleHome Directory Naming Convention
（5）Naming Subdirectories

Note:
Ensure that the paths you select for Oracle software, such as the Oracle home path and the Oracle base path, use only ASCII characters. Because installation owner names are used by default for some paths, this ASCII character restriction applies to user names, file names, and directory names.

3.2.1 Oracle Base Directory NamingConvention

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The Oracle Base directory is the top level directory that you can use to install the various Oracle software products. You can use the same Oracle base directory for multiple installations. If different operating system users install Oracle software on the same system, then each user must create a separate Oracle base directory.

Oracle Base目录是最顶层的目录，我们可以在这个目录下安装多套Oracle。不同的数据库可以使用相同的ORACLE BASE 目录。如果在同一个操作系统下用不同的OS用户来安装Oracle，那么每个OS 用户必须创建独立的ORACLE BASE 目录。

Name Oracle base directories using the syntax /pm/s/u. TableD-1 describes the variables used in this syntax.

ORACLE base 目录使用如下格式:/pm/s/u。具体每个参数的含义参考下表：

Table D-1 Syntax for Naming Oracle BaseDirectories

Oracle Documents 写道

For example, /u01/app/oracle is an Oracle base directory created by the oracle user and /u01/app/applmgr is an Oracle base directory created by the applmgr user.

Placing Oracle base directories at the same level in the UNIX file system is advantageous because it enables you to refer to the collection of Oracle base directories on different mount points using a single pattern matching string, /*/app/*.

3.2.2 Naming Mount Points for VeryLarge Databases (VLDBs)

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If each disk drive contains database files from one application and there are enough drives for each database to prevent I/O bottle necks, use the syntax /h/q/d for naming mount points. TableD-2 describes the variables used in this syntax.

如果每个磁盘存放一个应用的数据，从而来降低磁盘I/O的瓶颈，那么使用/h/q/d 的格式来挂载文件系统。具体参数含义参考下表：

Table D-2 Syntax for Naming Mount Points for Very Large Databases

For example, to allocate two drives exclusively for the test database, name the mount points /u01/app/oracle/oradata/test and /u02/app/oracle/oradata/test.

3.2.3 Referring to Path Names

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Refer to explicit（显示的） path names only in files designed specifically to store them, such as the password file, /etc/passwd,and the Oracle oratab file. Refer to group memberships only in the /etc/group file.

3.2.4 Oracle Home Directory NamingConvention

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To help fulfill the Optimal Flexible Architecture requirement of simultaneously running multiple versions of Oracle software, install the software in a directory matching the pattern /pm/s/u/product/v/type_[n].

为了保证多个版本的数据库同时运行，OFA的目录需要按照如下格式:/pm/s/u/product/v/type_[n]. 具体含义参考下表：

TableD-3 Syntax for Naming Oracle Home Directories

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For example:

/u01/app/oracle/product/11.2.0/dbhome_1 indicates the Oracle home directory for the first installation of Oracle Database on this system.

The ORACLE_HOME environment variable is set to the Oracle home directory.

3.2.5 Naming Subdirectories

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To facilitate the organization of administrative data, Oracle recommends that you store database-specific administration files in subdirectories matching the pattern /h/admin/d/a/, where h is the Oracle base directory, d is the database name (DB_NAME), and a is a subdirectory for specific types of database administration files. TableD-4 describes the database administration file subdirectories.

oracle 推荐的子目录使用如下格式：/h/admin/d/a, 这里h 是OracleBase，d 代表实例名，a 代表不同的类型。

Oracle Documents 写道

For example, /u01/app/oracle/admin/orcl/scripts/ is the scripts subdirectory associated with the database named orcl.

In Oracle Database11g, Automatic Diagnostic Repository (ADR) directories replace the bdump, cdump, and udump directories.The ADR diagnostic data goes into the /h/diag/rdbms/d/i/ directory.

where

h is Oracle Base，d is the database name，i is the instance name.

这里要注意的是，在Oracle 11g里面Oracle 使用ADR目录代替了bdump,cdump和udump。ADR的目录结构是/h/diag/rdbms/d/i.

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The ADR home has the trace, alert, and incident sub-directories. TableD-5 describes the ADR directories.

ADR目录有trace，alert 和其他的子目录，这些子目录如下表：

TableD-5 Locations for Diagnostic Traces

3.3 Naming Database Files

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The following table lists the recommended file naming conventions for database files:

Note:
Oracle Managed Files (OMF) and files stored in Oracle Automatic Storage Management disk groups use different naming conventions.

这里除了OMF，其文件存在放ASM里，有自己的命名约定。

The following table describes this syntax:

Oracle Documents 写道:

Note:
Do not store files other than control files, redo log files, or data files associated with database d in the path /h/q/d.

主要不要在/h/q/d 目录下存储除控制文件，online redo 和datafile 之外的文件。

Using this convention, it is easy to determine the database to which the /u01/app/oracle/oradata/sab/system01.dbf file belongs.

3.4 Separating Segments with Different Requirements

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Separate groups of segments with different life spans, I/O request demands, and backup frequencies across different tablespaces.

TableD-6 describes the special tablespaces that the Database Configuration Assistant creates for each Oracle database. If you manually create a database,you must create the required tablespaces. These tablespaces are in addition to those required for application segments.

根据不同的需求来创建对应的表空间，下表列出的是DBCA命令创建的所有表空间，其中的Example 和users 是可选的的表空间。

TableD-6 Special Tablespaces

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Creating these special tablespaces is effective because data dictionary segments are never dropped, and no other segments that can be dropped are allowed in the SYSTEM tablespace.

3.5 Exploitingthe Optimal Flexible Architecture Structure for Oracle Files

TableD-7 describes the syntax used for identifying classes of files.

TableD-7 Directory Structure Syntax for Identifying Classes of Files

3.6 Optimal Flexible Architecture File Mapping

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TableD-8 shows a hierarchical file mapping of a sample Optimal Flexible Architecture-compliant installation with two Oracle home directories and two databases. The database files are distributed across three mount points, /u02, /u03,and /u04.

Note:
Oracle recommends that you use Oracle ASM to provide greater redundancy and throughput.

TableD-8 Hierarchical File Mapping for an Optimal Flexible Architecture Installation