Creating a cluster

The following instructions explain how to create a cluster with one cluster member. The benefit of using the administrative console to create a cluster is that you can undo your changes as you go and you can use a graphical user interface.

1. Log in to the administrative console and navigate to Servers > Clusters > WebSphere application server clusters.
2. Click New to display the Create new cluster page.
3. From the Create new cluster page, enter basic cluster information:
   1. Type a name for the cluster in the Cluster name field.
   2. Select Prefer local if you want to enable host-scoped routing optimization. This option is enabled by default. When this option is enabled, if possible, EJB requests are routed to the client host. This option improves performance because client requests are sent to local enterprise beans.
      Note: If you enable the preferLocal optimization, the deployment manager must be running to affect the configuration. If the deployment manager is shut down, preferLocal optimization is not performed and requests might be dispersed across all the members of the cluster
   3. Select Configure HTTP session memory-to-memory replication if you want a memory-to-memory replication domain created for this cluster.

      The replication domain is given the same name as the cluster and is configured with the default settings for a replication domain. When the default settings are in effect, a single replica is created for each piece of data and encryption is disabled. Also, the Web container for each cluster member is configured for memory-to-memory replication.

      To change these settings for the replication domain, click Environment > Replication domains > replication_domain_name. To modify the Web container settings, click Servers > Clusters > WebSphere application server clusters > cluster_name > Clusters members > cluster_member_name. Then, in the Container settings section, click Web container settings > > Web container > Session management > Distributed environment settings in the administrative console. If you change these settings for one cluster member, you might also need to change them for the other members of this cluster.

4. Click Next to go to the Create first cluster member page.
5. From the Create first cluster member page, enter information about the cluster member.
   1. Enter the member name in the Member name field
   1. From the Select node list, click the node in which you want to define the server.
   2. In the Weight field, enter the weight value for the cluster member.
      The weight value controls the amount of work that is directed to the application server. If the weight value for this server is greater than the weight values that are assigned to other servers in the cluster, then this server receives a larger share of the workload. The weight value represents a relative proportion of the workload that is assigned to a particular application server. The value can range from 0 to 20.

      • On a z/OS system weight is used to balance some of the workload types, but others are balanced by the z/OS system. For HTTP requests, weights are used to distribute HTTP traffic between the Web server plug-in and the controller handling the clustered application server. Assign a higher weight value to the application server that should receive the HTTP traffic.
      • For Web services calls, information is transferred from a servant in one application server to a controller in another application server. The application server that receives the call has the highest weight value.
      • Weight has no affect on Internet Inter-ORB Protocol (IIOP) requests. IIOP requests are distributed to the correct application server using the sysplex distributor.
   3. Select Generate unique HTTP ports (the default option) if you want to generate unique port numbers for every HTTP transport that is defined in the source server.

      When this option is selected, this cluster member does not have HTTP transports or HTTP transport channels that conflict with any of the other servers that are defined on the same node. If you clear the Generate unique HTTP ports check box, all of the cluster members will share the same HTTP ports.

6. From the section, Select basis for first cluster member, select from the following options:
   • Create the member using an application server template

     This is the typical way of creating a cluster. Select defaultProcessServer.

     If you select this option and click Next, a blank form is displayed which you can use to define additional cluster members. The server you have just created is listed at the bottom of the screen.

     1. Click Next.
     2. Check the details on the summary screen and click Next.
     3. Save your configuration changes.

        The cluster you have just created is displayed in the list.

     4. Customize the port numbers to suit your configuration.
   • Create the member using an existing application server as a template

     This option is not supported.

   • Create the member by converting an existing application server
     Note: Do not select this option. WebSphere Application Server added a new parameter named resourcesScope to the createCluster and createClusterMember commands that allows you to control how the resources will be processed when the first cluster member is added to a cluster. Those parameters are described in the technote titled New parameter named resourcesScope was added to the createCluster and createClusterMember commands.
     It is required to use the resourcesScope parameter with the value cluster for IBM® Business Process Manager. The resourcesScope parameter is not currently exposed in the administrative console. Using the administrative console to create a cluster using an existing single server as the first cluster member is not supported on IBM Business Process Manager. Selecting this option will result in the following error message in the administrative console or the SystemOut.log of the deployment manager:

     resourcesScope parameter needs to be set to 'cluster' if creating a cluster from an existing server

     Using the command line to create a cluster using an existing single server as the first cluster member is valid. You must set the value of the resourcesScope to Cluster. For example,

     $AdminTask createCluster {-clusterConfig 
     {-clusterName newcluster -preferLocal true} 
     -convertServer {-serverNode NODE1Node01 -serverName testserver 
     -resourcesScope cluster}} 

     For information on the createCluster parameters, see ClusterConfigCommands command group for the AdminTask object in the WebSphere Application Server information center.

     For information on using the wsadmin tool to create cluster members, see Creating cluster members using scripting.

   • None

     Works always.

7. Click Next.
8. Create additional cluster members.
   Before you create additional cluster members, check the configuration settings of the first cluster member. These settings are displayed at the bottom of the Create additional cluster members panel of the Create a new cluster wizard. For each additional member that you want to create:

   1. Specify a unique name for the member. The name must be unique within the node.
   2. Select the node to which you want to assign the cluster member.
   3. Specify the weight you want given to this member. The weight value controls the amount of work that is directed to the application server. If the weight value for the server is greater than the weight values that are assigned to other servers in the cluster, then the server receives a larger share of the workload. The value can range from 0 to 20.
   4. Select Generate unique HTTP ports if you want to generate unique port numbers for every HTTP transport that is defined in the source server.
   5. Click Add member. You can edit the configuration settings of any of the newly created cluster members other than the first cluster member, or you can create additional cluster members. Click Previous to edit the properties of the first cluster member. The settings for the first cluster member become the settings for the cluster member template that is automatically created when you create the first cluster member.
9. When you finish creating cluster members, click Next.
10. View the summary of the cluster and then click Finish to create the cluster, click Previous to return to the previous wizard panel and change the cluster, or click Cancel to exit the wizard without creating the cluster.
11. To further configure a cluster, click Servers > Clusters > WebSphere application server clusters , and then click the name of the cluster. Only the Configuration and Local Topology tabs display until you save your changes.
12. Click Review to review your cluster configuration settings. Repeat the previous step if you need to make additional configuration changes.
13. If you do not want to make any additional configuration changes, select Synchronize changes with Nodes and then click Save. Your changes are saved and synchronized across all of your nodes.
    Note: If you click Save , but do not select Synchronize changes with Nodes, when you restart the cluster, the product does not start the cluster servers because it cannot find them on the node. If you want to always synchronize your configuration changes across your nodes, you can select Synchronize changes with Nodes as one of your console preferences.
14. Restart the cluster.