HomeOracle Page 7 - Getting Started with Oracle Database 10g
Oracle Database 10g Real Application Clusters - Oracle
This chapter explains the "g" in 10g and how to upgrade to 10g. Learn about the SYSAUX Tablespace, automatic storage management and Oracle Database 10g Real Application Clusters (chapter 1 from the book, Oracle Database 10g New Features, by Robert Freeman, McGraw/Hill-Osborne, 2004, ISBN: 0072229470).
Oracle9i Database introduced Real Application Clusters (RAC), which was a successor to Oracle Parallel Server. Oracle Database 10g offers several RAC-related improvements, including:
Cluster Ready Services
Enhancements to the Database Configuration Assistant and the Database Upgrade Assistant
Enhanced recovery parallelism on multiple CPU systems
A new parameter, gcs_server_processes
First introduced on limited platforms in Oracle9i Database, Portable Clusterware is now available on most Oracle Database 10g platforms. Clusterware provides clustering services for the Oracle Database 10g RAC configuration. Prior to Oracle Database 10g, most RAC configurations required that third-party clusterware software be purchased and installed. Now, in Oracle Database 10g, Oracle offers clusterware that runs on all platforms, eliminating the need for vendor-offered clusterware. Oracle's Portable Clusterware offers a number of features:
Infiniband high-speed network support
Simplified client installs
Simplified cluster installs
Oracle Database 10g provides for limited rolling upgrades for RAC clusters through the use of the opatch utility. These patches must be certified by Oracle to be used within a rolling upgrade scheme. There are a number of restrictions on what patches may be used as rolling upgrade patches, such as the fact that the patch cannot impact the contents of the database data dictionary and the patch cannot impact RAC internode communications. Rolling upgrades are available for one-off patches only as of this writing, thus patch sets cannot be applied in a rolling fashion.
Cluster Ready Services
Oracle Database 10g introduces Cluster Ready Services (CRS), which provides additional management services to a database cluster, such as node membership, group services, global resource management, and high availability. CRS also interacts with vendor-supplied software in its node management activities.
The Oracle Universal Installer will install CRS on nodes in an ORACLE_HOME location that is different from that of the RDBMS software's ORACLE_HOME install. As with the normal RDBMS software, you can install CRS on each individual node, or into a common ORACLE_HOME location for all the nodes.
CRS allows you to assign services to specific instances in the cluster, and these services can be configured in such a way as to allow you to manage the workload of the various machines of the cluster. Services are created within the DBCA, the Server Control utility, or the dbms_services PL/SQL stored procedure. You can administer services via Oracle Enterprise Manager (OEM) or the Server Control utility.
Oracle Database 10g provides statistics related to CRS within the Automatic Workload Repository (AWR). This allows you to manage cluster-related performance issues. Additionally, AWR provides the ability to monitor any specific performance thresholds that might be exceeded and send the DBA notification alerts based on these thresholds. Also, Oracle Database 10g provide an interface into CRS through the dbms_service and dbms_monitor PL/SQL procedures.
Oracle offers new functionality in two of the database assistant GUI programs, the Oracle Database Configuration Assistant (DBCA) and the Oracle Database Upgrade Assistant (DBUA). These assistants are built to make the DBA's job easier, by simplifying database configuration and migration to Oracle Database 10g. The DBCA can also be used to add and remove instances from the cluster. The DBCA now supports the creation and removal of clustered databases.
The DBCA will detect a clustered environment when it is executed and give you the opportunity to create a clustered database if that is your desire. The DBUA allows you to upgrade your previous RAC database to Oracle Database 10g with RAC.
NOTE: Oracle recommends that you create your clustered database with the DBCA in the Oracle Real Application Clusters Deployment and Performance Guide.
The gcs_server_processes Parameter
A new parameter, gcs_server_processes, is introduced in Oracle Database 10g. This parameter defines the initial number of server processes in Global Cache Service that are started to serve inter-instance traffic. The default value for this parameter is 2, and the value can range from 1 to 20. This parameter can also be set differently for each instance in the cluster.
This chapter is from Oracle Database 10g New Features, by Robert Freeman (McGraw-Hill/Osborne, 2004, ISBN: 0072229470). Check it out at your favorite bookstore today. Buy this book now.