What is Oracle Clusterware?

Oracle Clusterware provides the infrastructure necessary to run Oracle Real Application Clusters (Oracle RAC). Oracle Clusterware also manages resources, such as virtual IP (VIP) addresses, databases, listeners, services, and so on. These resources are generally named ora.entity_name.resource_type_abbreviation, such as ora.mydb.db, which is the name of a resource that is a database. (Some examples of abbreviation are db for database, lsnr for listener, and vip for VIP.) Oracle does not support editing these resources except under the explicit direction of My Oracle Support.

See Also:

Administering Oracle Clusterware and Making Applications Highly Available Using Oracle Clusterware for more information

Figure 1-1 shows a configuration that uses Oracle Clusterware to extend the basic single-instance Oracle Database architecture. In Figure 1-1, the cluster is running Oracle Database and is actively servicing applications and users. Using Oracle Clusterware, you can use the same high availability mechanisms to make your Oracle database and your custom applications highly available.

Figure 1-1 Oracle Clusterware Configuration

Description of Figure 1-1 follows
Description of "Figure 1-1 Oracle Clusterware Configuration"

The benefits of using a cluster include:

  • Scalability of applications

  • Reduce total cost of ownership for the infrastructure by providing a scalable system with low-cost commodity hardware

  • Ability to fail over

  • Increase throughput on demand for cluster-aware applications, by adding servers to a cluster to increase cluster resources

  • Increase throughput for cluster-aware applications by enabling the applications to run on all of the nodes in a cluster

  • Ability to program the startup of applications in a planned order that ensures dependent processes are started in the correct sequence

  • Ability to monitor processes and restart them if they stop

  • Eliminate unplanned downtime due to hardware or software malfunctions

  • Reduce or eliminate planned downtime for software maintenance

You can program Oracle Clusterware to manage the availability of user applications and Oracle databases. In an Oracle RAC environment, Oracle Clusterware manages all of the resources automatically. All of the applications and processes that Oracle Clusterware manages are either cluster resources or local resources.

Oracle Clusterware is required for using Oracle RAC; it is the only clusterware that you need for platforms on which Oracle RAC operates. Although Oracle RAC continues to support many third-party clusterware products on specific platforms, you must also install and use Oracle Clusterware. Note that the servers on which you want to install and run Oracle Clusterware must use the same operating system.

Using Oracle Clusterware eliminates the need for proprietary vendor clusterware and provides the benefit of using only Oracle software. Oracle provides an entire software solution, including everything from disk management with Oracle Automatic Storage Management (Oracle ASM) to data management with Oracle Database and Oracle RAC. In addition, Oracle Database features, such as Oracle Services, provide advanced functionality when used with the underlying Oracle Clusterware high availability framework.

Oracle Clusterware has two stored components, besides the binaries: The voting files, which record node membership information, and the Oracle Cluster Registry (OCR), which records cluster configuration information. Voting files and OCRs must reside on shared storage available to all cluster member nodes.