PRIMECLUSTER Installation and Administration Guide 4.2 (Linux)

6.7.7 Exclusive Relationships Between Cluster Applications

Set up exclusive relationships for the cluster applications to prevent cluster applications with exclusive relationships from operating simultaneously. An exclusive relationship can be set up only between standby cluster applications. If failover occurs, determine the cluster applications that should continue operating by using the job priority of the cluster applications between which an exclusive relationship is set.

Exclusive control is established between cluster applications within a single group.

• To set up an exclusive relationship, create a group of cluster applications between which an exclusive relationship is to be set. Up to 52 groups can be created.

• For information on setting up an exclusive relationship, see "Creating Standby Cluster Applications."

The operation of cluster applications, between which an exclusive relationship is set up, during failover can be explained in the following two cases:

• When the job priorities are different

• When the job priorities are the same

The example below explains the exclusive relationship between cluster applications within a single group. Even when there are multiple groups, the operation within a single group is the same.

When the job priorities of the cluster applications with an exclusive relationship are different

Cluster applications with the highest job priority take the top priority for startup on the nodes on which the cluster applications with high job priority are running or on the nodes to which the cluster applications with high job priority are failed over. Therefore, cluster applications with low priorities under a startup will be forcibly exited.

The states indicated in the following figure are as follows:

• OPERATING: The cluster application is in the Online state.

• STANDBY: The cluster application is in the Standby state.

• STOP: The cluster application is in the Offline state.

Failover of the cluster application with a high job priority

If failover occurs in a cluster application with a high job priority, the cluster application with the high job priority will always be in the operating state.

Failover of the cluster application with a low job priority

Failover occurs for a cluster application with a low job priority only when there is no cluster application with a high job priority included on the node to which the cluster application with a low job priority is to be failed over.

When the job priorities of cluster applications with an exclusive relationship are the same

The operation of the cluster applications that are already running will be continued. On the node on which cluster applications are already running, cluster applications that subsequently start up will be stopped.