Purpose – To setup Dynamic Clusters environment for WebSphere Application Server environment.

Pre-requisites –

RHEL or CentOS 7 with WAS ND v9 installed

What is Dynamic Clusters –

A dynamic cluster is an application deployment target that can expand and contract depending on the workload in your environment. Dynamic clusters work with autonomic managers, including the application placement controller and the dynamic workload manager to maximize the use of your computing resources.

It uses weights and workload management to balance the workloads of its cluster members dynamically, based on performance information that is collected from the cluster members. Dynamic clusters enable application server virtualization.

Dynamic Cluster Membership –

Automatically define cluster members with rules – In this cluster members are automatically defined based the membership policy.

Manually define cluster members – In this we statically define which servers are cluster members by selecting servers to add to the cluster

Procedure –

By default, if no rules are specified in the testodr – Routing policy HTTP rules section, all the requested contexts are accepted and are routed to the backend application servers within cell as shown below

Access the below URL and it should route the request to the server1 hosting the DefaultApplication.ear

In this step we are going to create a Dynamic Cluster with below values as explained in detail

wsadmin>AdminTask.createDynamicCluster(‘TestDynamicCluster’,'[-membershipPolicy “node_nodegroup = ‘DefaultNodeGroup'” -dynamicClusterProperties “[[operationalMode automatic][minInstances 0][maxInstances -1][numVerticalInstances 1][serverInactivityTime 1440]]” -clusterProperties “[[preferLocal false][createDomain false][templateName default][coreGroup DefaultCoreGroup]]”]’)

u’TestDynamicCluster(cells/desktop1Cell01/dynamicclusters/TestDynamicCluster|dynamiccluster.xml)’

wsadmin>AdminConfig.save()

wsadmin>AdminTask.listDynamicClusters()

u’TestDynamicCluster’

Once the dynamic cluster is created, it automatically add a cluster member DynamicCluster_Node name as shown above in the screenshot

Here are brief details about the parameters that are passed to create the cluster

membershipPolicy – Defines which node group the cluster members would be located

operationalMode – Specifies the operational mode. The valid values are: manual, supervised, and automatic

minInstances: Specifies the minimum number of cluster instances as an integer

maxInstances: Specifies the maximum number of cluster instances as an integer. If you do not want a limit to the number of cluster instances that can start, specify -1

numVerticalInstances: Specifies the number of instances that can start on the same node by creating vertical instances. Specify an integer value

preferLocal: Specifies whether enterprise bean requests are routed to the node on which the client resides when possible. The valid values are true or false

createDomain: Specifies that a replication domain is created for this cluster. Replication domains can be created only for WebSphere® Application Server application servers. The valid values are true or false

coreGroup: Specifies the name of the core group for the dynamic cluster. You only need to specify the core group for WebSphere Application Server application servers. The value can be DefaultCoreGroup or the core group name

templateName: Specifies the name of the server template. The valid input includes the following values

Once you try to access any one of the below URL’s , the request gets routed to the Dynamic Cluster member from ODR server and the Dynamic Cluster member is initiated/started up. You can verify the list of processes that are running after you try to access any of the below application

[root@desktop1 bin]# ps -ef | grep WebSphere | grep -v grep | awk ‘{print $NF}’

dmgr

nodeagent

testodr

TestDynamicCluster_desktop1Node01

Try to kill the Dynamic Cluster member process. In my case it is ‘6914’ process and see the process list again. It tries to restart the killed member instance again.

[root@desktop1 bin]# ps -ef | grep WebSphere | grep -v grep | awk ‘{print $2 ” ” $NF}’

3266 dmgr

5424 nodeagent

5812 testodr

[root@desktop1 bin]#

 [root@desktop1 bin]# kill -9 6914

[root@desktop1 bin]#

 [root@desktop1 bin]# ps -ef | grep WebSphere | grep -v grep | awk ‘{print $2 ” ” $NF}’

3266 dmgr

5424 nodeagent

5812 testodr

Hope you enjoyed reading this article. Thank you.