Preface

This manual prepares you to successfully implement clustered databases by presenting Real Application Clusters concepts. Information in this manual applies to Real Application Clusters as it runs on all operating systems. Real Application Clusters is a new, breakthrough architecture with scalability and high availability features that exceed the capabilities of previous Oracle cluster-enabled software releases.

You should read this manual before reading Oracle9i Real Application Clusters Installation and Configuration, Oracle9i Real Application Clusters Administration, and Oracle9i Real Application Clusters Deployment and Performance. For general information about Oracle and administering the single instance Oracle Server, refer to Oracle9i Database Concepts and Oracle9i Database Administrator's Guide.

This preface contains these topics:

Audience

Real Application Clusters Concepts is intended for database administrators and application developers who work with Real Application Clusters.

Organization

This book presents Real Application Clusters concepts in five parts. It begins by describing cluster database processing fundamentals for Real Application Clusters. The book then covers resource processing among instances. Next, it explains the fundamentals of how Real Application Clusters is implemented. Next, it describes High Availability and the Oracle Real Application Clusters Guard feature. It ends with reference material that includes an appendix describing the implementation restrictions on Real Application Clusters, an appendix on lock setting concepts, and a glossary of terms.

Part I "Cluster Database Processing Fundamentals"

Chapter 1, "Introduction to Real Application Clusters"

This chapter describes prerequisite knowledge, discusses terminology, and introduces cluster database processing and database technologies that offer advantages for online transaction processing and decision support applications.

Chapter 2, "Real Application Clusters Architecture"

This chapter describes the architectural components that Oracle provides for cluster database processing.

Chapter 3, "Cluster Hardware Architecture"

This chapter describes the hardware components and high-level architectural models that typify cluster environments.

Part II "Resource Coordination in Real Application Clusters"

Chapter 4, "Local Resource Coordination"

This chapter describes inter-instance coordination activities involved in a cluster and local resources employed by the Real Application Clusters software.

Chapter 5, "Cache Fusion and the Global Cache Service"

This chapter provides a detailed discussion of Cache Fusion and the inter-instance coordination activities handled by the Global Cache Service (GCS).

Chapter 6, "Coordination by the Global Enqueue Service"

This chapter provides details on and the inter-instance coordination activities handled by the Global Enqueue Service (GES).

Part III "Implementing Real Application Clusters"

Chapter 7, "Real Application Clusters Components"

This chapter describes the implementation components for Real Application Clusters applications.

Chapter 8, "Real Application Clusters Storage Considerations"

This chapter describes the storage considerations for Real Application Clusters applications.

Chapter 9, "Scalability in Real Application Clusters"

This chapter describes the scalability features of Real Application Clusters.

Part IV "High Availability"

Chapter 10, "High Availability Concepts and Best Practices"

This chapter describes the concepts and some best practices methodologies for how to use Real Application Clusters to implement high availability.

Chapter 11, "Oracle Real Application Clusters Guard Architecture"

This chapter describes the architecture of Oracle Real Application Clusters Guard.

Chapter 12, "Oracle Real Application Clusters Guard Operation"

This chapter describes the operation of Oracle Real Application Clusters Guard.

Part V "Reference"

Appendix A, "Restrictions"

This appendix lists restrictions of Real Application Clusters software.

Appendix B, "Using Multi-Block Lock Assignments (Optional)"

This appendix describes how to use optional lock setting to override the concurrency control provided by Cache Fusion.

Glossary

A glossary of Real Application Clusters and Oracle Real Application Clusters Guard terms.

Conventions

This section describes the conventions used in the text and code examples of the 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	Bold typeface indicates terms that are defined in the text or terms that appear in a glossary, or both.	The C datatypes such as ub4, sword, or OCINumber are valid. When you specify this clause, you create an index-organized table.
Italics	Italic typeface indicates book titles, emphasis, syntax clauses, or placeholders.	Oracle9i Database Concepts You can specify the parallel_clause. Run `U``old_release``.SQL` where old_release refers to the release you installed prior to upgrading.
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, user names, and roles.	You can specify this clause only for a `NUMBER` column. You can back up the database using the `BACKUP` command. Query the `TABLE_NAME` column in the `USER_TABLES` data dictionary view. Specify the `ROLLBACK_SEGMENTS` parameter. Use the `DBMS_STATS`.`GENERATE_STATS` procedure.
lowercase monospace (fixed-width font)	Lowercase monospace typeface indicates executables 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, user names and roles, program units, and parameter values.	Enter `sqlplus` to open SQL*Plus. 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.

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.	`{ENABLE \| DISABLE}`
\|	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.	`{ENABLE \| DISABLE}` `[COMPRESS \| NOCOMPRESS]`
`...`	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, ... , col``n` `FROM employees;`
. . .	Vertical ellipsis points indicate that we have omitted several lines of code not directly related to the example.
Other notation	You must enter symbols other than brackets, braces, vertical bars, and ellipsis points as it is shown.	`acctbal NUMBER(11,2);` `acct CONSTANT NUMBER(4) := 3;`
`Italics`	Italicized text indicates variables for which you must supply particular values.	`CONNECT SYSTEM/``system_password`
`UPPERCASE`	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 employees;` `SELECT * FROM USER_TABLES;` `DROP TABLE hr.employees;`
`lowercase`	Lowercase typeface indicates programmatic elements that you supply. For example, lowercase indicates names of tables, columns, or files.	`SELECT last_name, employee_id FROM employees;` `sqlplus hr/hr`

Documentation Accessibility

Oracle's goal is to make our products, services, and supporting documentation accessible to the disabled community with good usability. To that end, our documentation includes features that make information available to users of assistive technology. This documentation is available in HTML format, and contains markup to facilitate access by the disabled community. Standards will continue to evolve over time, and Oracle is actively engaged with other market-leading technology vendors to address technical obstacles so that our documentation can be accessible to all of our customers. For additional information, visit the Oracle Accessibility Program Web site at

http://www.oracle.com/accessibility/

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.