Book Image

Oracle 11g R1 / R2 Real Application Clusters Handbook

Book Image

Oracle 11g R1 / R2 Real Application Clusters Handbook

Overview of this book

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. RAC is an integral part of the Oracle database setup: one database, 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 practical handbook documents how to administer a complex Oracle 11g RAC environment. It covers all areas of the Oracle 11g R1 RAC environment, with bonus R2 information included, and is indispensable if you are an Oracle DBA charged with configuring and implementing Oracle11g. It presents a complete method for the design, installation, and configuration of Oracle 11g RAC, ultimately enabling rapid administration of Oracle 11g RAC environments.Packed with real-world examples, expert tips, and troubleshooting advice, the book begins by introducing the concept of RAC and High Availability. It then dives deep into the world of RAC design, installation, and configuration, enabling you to support complex RAC environments for real-world deployments. Chapters cover 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 the 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 in real-world situations.
Table of Contents (20 chapters)
Oracle 11g R1/R2 Real Application Clusters Handbook
Credits
About the Authors
About the Reviewers
Preface

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 11gR2 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. 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. 2. Use the -force flag to stop partial or failed 11gR2 upgrades. However, this command neither resets the OCR nor deletes ocr.loc.

  3. 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 RID_HOME/crs/install directory and execute the following sample command:

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