Book Image

Oracle 11g R1/R2 Real Application Clusters Essentials

Book Image

Oracle 11g R1/R2 Real Application Clusters Essentials

Overview of this book

Oracle RAC or Real Application Clusters is a grid computing solution that allows multiple nodes (servers) in a clustered system to mount and open a single database that resides on shared disk storage. Should a single system (node) fail, the database service will still be available on the remaining nodes. Oracle RAC is an integral part of the Oracle database setup. You have one database with multiple users accessing it, in real time. This book will enable DBAs to get their finger on the pulse of the Oracle 11g RAC environment quickly and easily.This book will cover all areas of the Oracle RAC environment and is indispensable if you are an Oracle DBA who is charged with configuring and implementing Oracle11g R1, with bonus R2 information included. This book presents a complete method for the configuration, installation, and design of Oracle 11g RAC, ultimately enabling rapid administration of Oracle 11g RAC environments.This practical handbook documents how to administer a complex Oracle 11g RAC environment. Packed with real world examples, expert tips and troubleshooting advice, the book begins by introducing the concept of Oracle RAC and High Availability. It then dives deep into the world of RAC configuration, installation and design, enabling you to support complex RAC environments for real world deployments. Chapters cover Oracle RAC and High Availability, Oracle 11g RAC Architecture, Oracle 11g RAC Installation, Automatic Storage Management, Troubleshooting, Workload Management and much more. By following the practical examples in this book, you will learn every concept of the RAC environment and how to successfully support complex Oracle 11g R1 and R2 RAC environments for various deployments within real world situations. This book is the updated release of our previous Oracle 11g R1/R2 Real Application Clusters Handbook. If you already own a copy of that Handbook, there is no need to upgrade to this book.
Table of Contents (20 chapters)
Oracle 11g R1/R2 Real Application Clusters Essentials
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Preface
Index

Downgrading Oracle Clusterware after an upgrade


For any technical or non-technical reason, you may want to downgrade a successful or failed upgrade of Oracle Clusterware 11g R2 to the previous version as it was before 11g R2. In order to do so, you will need to complete the following downgrade procedure:

  1. As root, navigate through the $GRID_HOME/crs/install directory and execute the rootcrs.pl –downgrade script on all nodes in a cluster. This script will stop the resources and shut down the cluster stack on the node.

    /u01/app/11.2.0/grid/crs/install/rootcrs.pl –downgrade [-force]
  2. Use the –force flag to stop partial or failed 11g R2 upgrades. However, this command neither resets the OCR nor deletes ocr.loc.

  3. After the rootcrs.pl –downgrade script is successfully executed on all nodes, as the root user on the local Node 1 of the cluster, you will need to navigate through the GRID_HOME/crs/install directory and execute the following sample command:

    /u01/app/11.2.0/grid/crs/install/rootcrs.pl –downgrade...