This chapter provides an overview of clustered systems.
A clustered system uses two or more server machines as a single virtual server machine to provide high level of availability.
In single-server machine operation, if the server machine or an application running on it stops, the machine or the application must be restarted. During this time, the operation stops.
A clustered system, however, uses two or more server machines. If a failure occurs on one server machine or an application running on it, the transaction can be resumed immediately by restarting the application on the other server machine. As a result, transaction downtime is reduced. The switching of a transaction from a server with a problem to another server that is operating normally is referred to as failover.
In the clustered system, the server machines are collectively called a cluster, and each server machine in the cluster is called a node.
The cluster operation is classified into one of the following types. These types are explained in names of "PRIMECLUSTER".
Standby operation
1:1 standby
Mutual standby
N:1 standby
Cascade
Priority transfer
Scalable operation
See
The cluster operation and the names given to those that are supported with a clustered system differ from each other in different systems. Refer to the cluster software manuals for more information.
