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Oracle® High Availability Architecture and Best Practices
10g Release 1 (10.1)

Part Number B10726-01
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This book is a database high availability reference. It describes Oracle database architectures and features as well as recommended practices that can help your business achieve high availability. It provides guidelines for choosing the appropriate high availability solution.

This preface contains these topics:


This book is intended for chief technology officers, information technology architects, database administrators, system administrators, network administrators, and application administrators who perform the following tasks:


This document contains:

Part I, "Getting Started"

This part provides an overview of high availability (HA) and describes the Oracle features that can be used to achieve high availability.

Chapter 1, "Overview of High Availability"

This chapter defines high availability and the need for HA architecture and practices. It describes in general terms what is necessary to achieve high availability. It gives examples of outages and their impact on businesses. It also explains the scope of the book and how to use the book.

Chapter 2, "Determining Your High Availability Requirements"

This chapter describes service level agreements and business requirements. It provides guidelines for determining whether data loss is acceptable and discusses the performance and manageability impact of HA practices.

Part II, "Oracle Database High Availability Features, Architectures, and Policies"

This part explains what business requirements influence the decision to implement a high availability solution. After the essential factors have been identified, defined, and described, the factors are used to provide guidance about choosing a high availability architecture.

Chapter 3, "Oracle Database High Availability Features"

This chapter provides high-level descriptions of Oracle HA features.

Chapter 4, "High Availability Architectures"

This chapter describes validated HA architectures.

Chapter 5, "Operational Policies for High Availability"

This chapter describes operational best practices for HA.

Part III, "Configuring a Highly Available Oracle Environment"

This part describes how to configure the high availability architectures.

Chapter 6, "System and Network Configuration"

This chapter provides recommendations for configuring the subcomponents that make up the database server tier and the network.

Chapter 7, "Oracle Configuration Best Practices"

This chapter recommends Oracle configuration and best practices for the database, Oracle Real Application Clusters, Oracle Data Guard, Maximum Availability Architecture, backup and recovery, and fast application failover.

Part IV, "Managing a Highly Available Oracle Environment"

This part describes how to manage an HA Oracle environment.

Chapter 8, "Using Oracle Enterprise Manager for Monitoring and Detection"

This chapter describes how to monitor and detect system availability. It emphasizes Oracle Enterprise Manager.

Chapter 9, "Recovering from Outages"

This chapter contains a decision matrix for determining what actions to take for specific outages.

Chapter 10, "Detailed Recovery Steps"

This chapter contains detailed steps for recovering from the outages described in Chapter 9, "Recovering from Outages".

Chapter 11, "Restoring Fault Tolerance"

This chapter describes the following types of repair: restoring failed nodes in a Real Application Cluster, restoring the standby database after a failover, restoring fault tolerance after secondary site or clusterwide scheduled outage, restoring fault tolerance after a standby database data failure, restoring fault tolerance after the production database is activated, and restoring fault rolerance after dual failures.

Appendix A, "Hardware Assisted Resilient Data (HARD) Initiative"

This appendix contains information about the Hardware Assisted Resilient Data (HARD) initiative.

Appendix B, "Database SPFILE and Oracle Net Configuration File Samples"

This appendix contains database SPFILE and Oracle Net configuration file samples.

Related Documentation

For more information, see the Oracle database documentation set. These books may be of particular interest:

Many books in the documentation set use the sample schemas of the seed database, which is installed by default when you install Oracle. Refer to Oracle Database Sample Schemas for information on how these schemas were created and how you can use them yourself.

Printed documentation is available for sale in the Oracle Store at

To download free release notes, installation documentation, white papers, or other collateral, please visit the Oracle Technology Network (OTN). You must register online before using OTN; registration is free and can be done at

If you already have a username and password for OTN, then you can go directly to the documentation section of the OTN Web site at


This section describes the conventions used in the text and code examples of this documentation set. It describes:

Conventions in Text

We use various conventions in text to help you more quickly identify special terms. The following table describes those conventions and provides examples of their use.

Convention Meaning Example


Bold typeface indicates terms that are defined in the text or terms that appear in a glossary, or both.

When you specify this clause, you create an index-organized table.


Italic typeface indicates book titles or emphasis.

Oracle Database Concepts

Ensure that the recovery catalog and target database do not reside on the same disk.

UPPERCASE monospace (fixed-width) font

Uppercase monospace typeface indicates elements supplied by the system. Such elements include parameters, privileges, datatypes, RMAN keywords, SQL keywords, SQL*Plus or utility commands, packages and methods, as well as system-supplied column names, database objects and structures, usernames, and roles.

You can specify this clause only for a NUMBER column.

You can back up the database by using the BACKUP command.

Query the TABLE_NAME column in the USER_TABLES data dictionary view.


lowercase monospace (fixed-width) font

Lowercase monospace typeface indicates executables, filenames, directory names, and sample user-supplied elements. Such elements include computer and database names, net service names, and connect identifiers, as well as user-supplied database objects and structures, column names, packages and classes, usernames and roles, program units, and parameter values.

Note: Some programmatic elements use a mixture of UPPERCASE and lowercase. Enter these elements as shown.

Enter sqlplus to open SQL*Plus.

The password is specified in the orapwd file.

Back up the datafiles and control files in the /disk1/oracle/dbs directory.

The department_id, department_name, and location_id columns are in the hr.departments table.

Set the QUERY_REWRITE_ENABLED initialization parameter to true.

Connect as oe user.

The JRepUtil class implements these methods.

lowercase italic monospace (fixed-width) font

Lowercase italic monospace font represents placeholders or variables.

You can specify the parallel_clause.

Run Uold_release.SQL where old_release refers to the release you installed prior to upgrading.

Conventions in Code Examples

Code examples illustrate SQL, PL/SQL, SQL*Plus, or other command-line statements. They are displayed in a monospace (fixed-width) font and separated from normal text as shown in this example:

SELECT username FROM dba_users WHERE username = 'MIGRATE';

The following table describes typographic conventions used in code examples and provides examples of their use.

Convention Meaning Example
[ ]

Brackets enclose one or more optional items. Do not enter the brackets.

DECIMAL (digits [ , precision ])
{ }

Braces enclose two or more items, one of which is required. Do not enter the braces.


A vertical bar represents a choice of two or more options within brackets or braces. Enter one of the options. Do not enter the vertical bar.


Horizontal ellipsis points indicate either:

  • That we have omitted parts of the code that are not directly related to the example
  • That you can repeat a portion of the code

CREATE TABLE ... AS subquery;

SELECT col1, col2, ... , coln FROM 

Vertical ellipsis points indicate that we have omitted several lines of code not directly related to the example.

9 rows selected.

Other notation

You must enter symbols other than brackets, braces, vertical bars, and ellipsis points as shown.

acctbal NUMBER(11,2);
acct    CONSTANT NUMBER(4) := 3;

Italicized text indicates placeholders or variables for which you must supply particular values.

CONNECT SYSTEM/system_password
DB_NAME = database_name


Uppercase typeface indicates elements supplied by the system. We show these terms in uppercase in order to distinguish them from terms you define. Unless terms appear in brackets, enter them in the order and with the spelling shown. However, because these terms are not case sensitive, you can enter them in lowercase.

SELECT last_name, employee_id FROM 
DROP TABLE hr.employees;

Lowercase typeface indicates programmatic elements that you supply. For example, lowercase indicates names of tables, columns, or files.

Note: Some programmatic elements use a mixture of UPPERCASE and lowercase. Enter these elements as shown.

SELECT last_name, employee_id FROM 
sqlplus hr/hr

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Accessibility of Code Examples in Documentation

JAWS, a Windows screen reader, may not always correctly read the code examples in this document. The conventions for writing code require that closing braces should appear on an otherwise empty line; however, JAWS may not always read a line of text that consists solely of a bracket or brace.

Accessibility of Links to External Web Sites in Documentation

This documentation may contain links to Web sites of other companies or organizations that Oracle does not own or control. Oracle neither evaluates nor makes any representations regarding the accessibility of these Web sites.