Oracle Clusterware

Oracle Clusterware is:

• A key part of Oracle Grid Infrastructure 
• Integrated with Oracle Automatic Storage Management (ASM)
• The basis for ASM Cluster File System (ACFS)
• A foundation for Oracle Real Application Clusters (RAC)
• A generalized cluster infrastructure for all kinds of applications

Oracle Clusterware is a key part of Oracle Grid Infrastructure, which also includes Automatic Storage Management (ASM) and the ASM Cluster File System (ACFS).

In Release 11.2, Oracle Clusterware can use ASM for all the shared files required by the cluster. Oracle Clusterware is also an enabler for the ASM Cluster File System, a generalized cluster file system that can be used for most file-based data such as documents, spreadsheets, and reports.

The combination of Oracle Clusterware, ASM, and ACFS provides administrators with a unified cluster solution that is not only the foundation for the Oracle Real Application Clusters (RAC) database, but can also be applied to all kinds of other applications.

Note: Grid Infrastructure is the collective term that encompasses Oracle Clusterware, ASM, and ACFS. These components are so tightly integrated that they are often collectively referred to as Oracle Grid Infrastructure.

What Is Clusterware?

Clusterware is a term used to describe software that provides interfaces and services that enable and support a cluster.

Different cluster architectures require clusterware that delivers different services. For example, in a simple failover cluster, the clusterware may monitor the availability of applications and perform a failover operation if a cluster node becomes unavailable. In a load balancing cluster, different services are required to support workload concurrency and coordination.

Typically, clusterware includes capabilities that:

• •Allow the cluster to be managed as a single entity (not including OS requirements), if desired
• •Protect the integrity of the cluster so that data is protected and the cluster continues to function even if  communication with a cluster node is severed
• •Maintain a registry of resources so that their location is known across the cluster and so that  dependencies between resources is maintained
• •Deal with changes to the cluster such as node additions, removals, or failures • Provide a common  view of resources such as network addresses and files in a file system

What Is a Cluster?

A cluster consists of two or more independent, but interconnected, servers. Several hardware vendors have

provided cluster capability over the years to meet a variety of needs. Some clusters were intended only to provide high availability by allowing work to be transferred to a secondary node if the active node fails. Others were designed to provide scalability by allowing user connections or work to be distributed across the nodes.

Another common feature of a cluster is that it should appear to an application as if it were a single server. Similarly, management of several servers should be as similar to the management of a single server as possible. The cluster management software provides this transparency.

For the nodes to act as if they were a single server, files must be stored in such a way that they can be found by the specific node that needs them. There are several different cluster topologies that address the data access issue, each dependent on the primary goals of the cluster designer.

The interconnect is a physical network used as a means of communication between each node of the cluster. In short, a cluster is a group of independent servers that cooperate as a single system.

Note: The clusters you are going to manipulate in this course all have the same operating system. This is a requirement for RAC clusters.

Oracle Grid Infrastructure

ASM and Oracle Clusterware are installed into a single home directory called the Grid Infrastructure home.

With Oracle Database 11g Release 2, Automatic Storage Management (ASM) and Oracle Clusterware are installed into a single home directory, collectively called Oracle Grid Infrastructure. This directory is referred to as the Grid Infrastructure home. Configuration assistants start after the Oracle Universal Installer interview process and binary installation that configure ASM and Oracle Clusterware. Although the installation is called Oracle Grid Infrastructure, Oracle Clusterware and Automatic Storage Manager remain separate components.

A History of Innovation