About the Cold Failover Cluster Configuration

A cluster is a collection of interconnected usable whole computers that is used as a single computing resource. Hardware clusters provide high availability and scalability.

During failover, an application running on one cluster node is transparently migrated to another cluster node. During this migration, clients accessing the service on the cluster see a momentary outage and may need to reconnect once the failover is complete.

The cluster node on which the application runs at any given time is called the primary node. The cluster node to which the application is moved during a failover is called the secondary node.

In a hardware cluster, each physical node has its own physical IP address and physical host name. To present a single system image to the outside world, the cluster uses a dynamic IP address that can be moved to any physical node in the cluster. This is called the virtual IP address. The host name corresponding to this virtual IP address is called the logical or virtual host name. All network clients accessing a service on the cluster in a cold failover configuration use the virtual host name.

A logical host consists of one or more disk groups, and pairs of host names and IP addresses. It is mapped to a physical host in the cluster. This physical host impersonates the host name and IP address of the logical host.

Although each node is a usable whole computer, in most cases the storage subsystem is shared by all the nodes. In a cold failover cluster configuration, the shared storage subsystem hosts the Oracle Internet Directory installation--that is, the ORACLE_HOME--and at any given point in time is accessible by one active node.