Create a cluster: Create first cluster member
Specify settings for the first cluster member.
There are two ways to create the first member of a cluster:
- Create the first member when we create a cluster.
To create a cluster, in the administrative console, click...
Servers > Clusters > WebSphere application server clusters > New.
- Create an empty cluster and then add a first member after you finish creating the cluster.
To create a cluster member for an existing cluster, in the administrative console, click...
Servers > Clusters > WebSphere application server clusters > cluster_name > Clusters members > New.
When creating the first cluster member, a copy of that member is stored as part of the cluster data and becomes the template for all additional cluster members that we create.
When adding servers to a cluster, remember that the only way to remove an application server from a cluster is to delete the application server from the list of cluster members.
Member name
Name of the application server created for the cluster.
The member name must be unique on the selected node.
Select node
Node on which the application server resides.
(ZOS) Short name
Short name for this cluster member. This field only applies to the z/OS platform.
The short name is the default z/OS job name and identifies the cluster member to the native facilities of the operating system, such as Workload Manager (WLM), Automatic Restart Manager, SAF (for example, RACF ), started task control, and others.
If we specify a short name for a cluster member, the name:
- Must be one to eight characters in length. By default, WebSphere Application Server for z/OS assumes that we are using a 7-character server short name (JOBNAME). If our naming standards require 8 characters, we can lengthen the 7-character server short name to 8 characters.
- Must contain only uppercase alphanumeric characters
- Cannot start with a number.
- Must be unique in the cell
- Cannot be the same as the value specified on the ClusterTransitionName custom property of any non-clustered server. Do not specify a cluster transition name for a server that is part of a cluster.
If we do not specify a short name, the system assigns a default short name that is automatically unique within the cell. We can change the generated short name to conform with your naming conventions.
Weight
Amount of work that is directed to the application server.
If the weight value for the server is greater than the weight values assigned to other servers in the cluster, the server receives a larger share of the cluster workload. The value can range from 0 to 20. Enter zero to indicate that we do not want requests to route to this application server unless this server is the only server available to receive requests.
(ZOS) On z/OS, 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.
Core group
Core group in which the application server resides. This field displays only if we have multiple core groups configured. We can change this value only for the first cluster member.
Generate unique HTTP ports
That a unique HTTP port is generated for the application server. By generating unique HTTP ports for the application server, you avoid potential port collisions and configurations that are not valid.
Select how the server resources are promoted in the cluster
Specifies how resources such as data sources and schedulers are initially created in the cluster. Create settings at the cluster scope if the settings can be used across the entire cluster. Otherwise, create settings at the cluster member (server) level. Creating settings at the cluster scope reduces the amount of configuration that you maintain.
When we create a cluster, this setting is disabled if we select None. Create an empty cluster for the Select basis for first cluster member setting. Otherwise, this setting is enabled.
The list has the following options.
- Cluster
- Moves the resources of the first cluster member to the cluster level. The resources of the first cluster member replace the resources of the cluster. Move resources of the first cluster member when we want to promote the resources of a server to the cluster. Promoting resources is the recommended option.
- The Cluster option is the default behavior in the administrative console.
- Server
- Maintains the server resources at the new cluster member level and does not change the cluster level resources.
The Server option is most useful in the following situations:
- When we want different configuration settings for resources defined on each cluster member.
- When we have deleted all of our cluster members and want to create new cluster members. However, we do not want to replace the cluster scoped resources when we create the cluster members.
- Both
- Copies the resources of the cluster member (server) to the cluster level. The resources of the first cluster member replace the resources of the cluster. The same resources exist at both the cluster and cluster member scopes.
Important: These options are available only for the first cluster member. All other members of a cluster are based on the cluster member template which is created from the first cluster member.
Select basis for first cluster member
Basis we want to use for the first cluster member.
- If we select Create the member using an application server template, the settings for the new application server are identical to the settings of the application server template we select from the list of available templates.
(ZOS) If we select the defaultZOS template, which is the only one listed unless we used the createApplicationServerTemplate command for the AdminTask object to create additional templates, the first cluster member uses the default port assignments for the z/OS platform. If some of these ports are already defined for use elsewhere in your z/OS system, the newly created cluster member might not start, might function incorrectly, or might generate unexpected error messages. Therefore, we must resolve any port conflicts before starting this server.
- If we select Create the member using an existing application server as a template, the settings for the new application server are identical to the settings of the application server we select from the list of existing application servers.
- If we select Create the member by converting an existing application server, the application server we select from the list of available application servers becomes a member of this cluster.
- If we select None. Create an empty cluster, a new cluster is created but it does not contain any cluster members.
Important: The basis options are available only for the first cluster member. All other members of a cluster are based on the cluster member template which is created from the first cluster member.
Related:
Clusters and workload management Create clusters Create a cluster: Basic cluster settings Create a cluster: Create additional cluster members Create a cluster: Summary settings Commands for the AdminTask object