Examples: Using node groups

Use node groups to define groups of nodes capable of hosting members of the same cluster. An application deployed to a cluster must be capable of running on any of the cluster members. This means that the node that hosts each of the cluster members must be configured with software and settings necessary to support running of the application.

By organizing nodes that satisfy your application requirements into a node group, you establish an administrative policy that governs which
nodes can be used together to form a cluster. The people who define the cell configuration and the people who create server clusters can operate with greater independence from one another, if they are different people.

Example 1 Assume the following information:

• A cell is comprised of nodes 1 to 8.

• Each node is a managed node, which means that each node is configured with an Application Server.

• Nodes 6, 7, and 8 are additionally configured as WebSphere Business Integration Server Foundation nodes.

• All nodes are either z/OS system nodes from the same sysplex, or distributed platform nodes. An OS/400 node is considered a distributed platform node.

• By default, all the nodes are in the default node group, DefaultNodeGroup.

Applications that exploit WebSphere Business Integration Server Foundation functions can run successfully only on nodes 6, 7, and 8. Therefore,
clusters that host these applications can be formed only on nodes 6, 7, and 8. To define a clustering policy that guides users of your WebSphere cell into building clusters that can only span predetermined nodes, create an additional node group called WBINodeGroup, for example. Add to the node group nodes 6, 7, and 8. If you create a cluster on a node from the WBINodeGroup node group, the system allows only nodes from the WBINodeGroup node group to be members of the cluster.

Example 2

Note: OS/400 nodes are considered to be distributed platform nodes. Assume the following information:

• A cell is comprised of nodes 1 to 6.

• Each node is a managed node, which means that each node is configured with an Application Server.

• Nodes 1 to 4 are on distributed platforms.

• Nodes 5 and 6 are nodes on the z/OS operating system and are in sysplex PLEX1.

• The deployment manager is on a distributed platform node.

• Nodes 1 to 4 are members of the DefaultNodeGroup node group by default.

• You created empty node group PLEX1NodeGroup to group the z/OS operating system nodes on the PLEX1 sysplex.

• You joined the nodes on the z/OS operating system to the PLEX1NodeGroup node group when you added them to the cell. You did this because nodes on the z/OS operating system cannot be in the same node group as the distributed platform nodes.

Applications that exploit z/OS functions in the PLEX1 sysplex can run successfully only on nodes 5 and 6. Therefore, clusters that host these applications can be formed only on nodes 5 and 6. The required separation of distributed platform nodes from z/OS system nodes establishes a natural clustering policy that guides users of your Application Server cell into building
clusters that can only span predetermined nodes. If you create a cluster on a node from the PLEX1NodeGroup node group, the system allows only nodes from the PLEX1NodeGroup node group to be members of the cluster.

Related concepts
Node group membership rules

Related reference
Node group collection