Oracle RAC is a cluster database with a shared cache architecture that overcomes the limitations of traditional shared-nothing and shared-disk approaches to provide a highly scalable and available database solution for all your business applications. Oracle RAC provides the foundation for enterprise grid computing.
Oracle’s Real Application Clusters (RAC) option supports the transparent deployment of a single database across a cluster of servers, providing fault tolerance from hardware failures or planned outages. Oracle RAC running on clusters provides Oracle’s highest level of capability in terms of availability, scalability, and low-cost computing.
One DB opened by multipe instances so the the db ll be Highly Available if an instance crashes.
Cluster Software. Oracles Clusterware or products like Veritas Volume Manager are required to provide the cluster support and allow each node to know which nodes belong to the cluster and are available and with Oracle Cluterware to know which nodes have failed and to eject then from the cluster, so that errors on that node can be cleared.
Oracle Clusterware has two key components Cluster Registry OCR and Voting Disk.
The cluster registry holds all information about nodes, instances, services and ASM storage if used, it also contains state information ie they are available and up or similar.
The voting disk is used to determine if a node has failed, i.e. become separated from the majority. If a node is deemed to no longer belong to the majority then it is forcibly rebooted and will after the reboot add itself again the the surviving cluster nodes.
Oracle’s Real Application Clusters (RAC) option supports the transparent deployment of a single database across a cluster of servers, providing fault tolerance from hardware failures or planned outages. Oracle RAC running on clusters provides Oracle’s highest level of capability in terms of availability, scalability, and low-cost computing.
One DB opened by multipe instances so the the db ll be Highly Available if an instance crashes.
Cluster Software. Oracles Clusterware or products like Veritas Volume Manager are required to provide the cluster support and allow each node to know which nodes belong to the cluster and are available and with Oracle Cluterware to know which nodes have failed and to eject then from the cluster, so that errors on that node can be cleared.
Oracle Clusterware has two key components Cluster Registry OCR and Voting Disk.
The cluster registry holds all information about nodes, instances, services and ASM storage if used, it also contains state information ie they are available and up or similar.
The voting disk is used to determine if a node has failed, i.e. become separated from the majority. If a node is deemed to no longer belong to the majority then it is forcibly rebooted and will after the reboot add itself again the the surviving cluster nodes.