(ZOS) Automatically rolling out updates to a high availability application
We can set up the system to perform automatic application rollout for our high availability applications. The automatic application rollout update process stops or pauses each application server hosting a cluster member that needs updating.
Determine which application servers are hosting the cluster members that need updating.
If we have a high availability application that frequently requires updates, we might want to automatically control the rollout of these updates.
When setting up the rollout update process we must decide whether we want the application servers to stop or pause while the update is made to an application. If we want the servers to pause, configure the node agent to allow the rollout update process to pause and resume the servers. We do not have to make any configuration changes if we want the rollout update process to stop and start the servers. However if the rollout update process stops and starts the servers, the process takes much longer to complete.
When an application server pauses, all requests already in the queue for that server are allowed to complete, but no new requests are accepted. Both the sysplex distributor and the WebSphere Application Server web server plug-in route work away from the server that is paused. After all of the requests assigned to that server complete, the application update process starts on that server.
When the update process is complete, the listener for that server resumes and the sysplex distributor and the WAS web server plug-in assign new work to that server. This process is repeated for all of the other servers in the cluster until all of the affected cluster members are updated.
To prepare the system to automatically rollout updates to a high availability application:
Tasks
- Determine whether we want the rollout update process to stop or pause the affected application servers.
- If we want the rollout update process to stop a server before it performs an application update, go to step 5.
- If we want the rollout process to pause a server before it performs an application update, go to step 2. Steps 2, 3, and 4 are configuration changes that enable the rollout update process to pause and resume servers during an application update. You only have to make these changes once.
These configuration changes involve setting com.ibm.websphere.zos.mvsservices.enable and com.ibm.websphere.zos.rollout.pauseresume to true. These custom properties PAUSE/RESUME instead of STOP/START servers on z/OS. Setting these properties to true avoids the overhead of stopping and starting servers during the rollout update process. Be aware that when active requests are pending during the rollout update process, these active requests are stopped.
- Add the com.ibm.websphere.zos.mvsservices.enable and com.ibm.websphere.zos.rollout.pauseresume custom properties to the node agent settings in the master configuration repository on the deployment manager server. These properties must be added to the settings for all of the node agents on which we want to automatically start the MVSServices MBean.
- In the administrative console, click...
System Administration > Node agents > node_agent_name > Administration Services > Custom Properties > New
- Enter com.ibm.websphere.zos.mvsservices.enable in the Name field, and true in the Value field.
- Click Ok .
- Click New .
- Enter com.ibm.websphere.zos.rollout.pauseresume in the Name field, and true in the Value field.
- Click Ok .
- Repeat these steps for any other node agents on which we want to automatically start the MVSServices MBean.
- Click Save to save the changes directly to the master configuration.
After adding the com.ibm.websphere.zos.rollout.pauseresume custom property and set it to true, any future application rollouts on this node are accomplished by pausing a listener for the application server, rather than stopping that application server.
If the custom property com.ibm.websphere.zos.rollout.pauseresume is set to true, but the MVSServices MBean is not running on the configured node, the application servers on that node do not pause, and are not updated during the application update process.
Messages are displayed on the MVS™ Console when an application server is paused or resumed similar to the messages displayed when an application server is stopped or started.
- Restart the node agent. When we restart the node agent, the MVSServices MBean automatically starts.
- Update the application configuration repository in the master on the deployment manager server.
We are ready to start the rollout update process for an application needed to update.
What to do next
To start the rollout update process, in the administrative console, click Applications > Enterprise Applications, select the application to update, and click Rollout Update.
The application we select must reside on at least one member of a cluster.
This function automatically stops or pauses the server, updates the application, and then starts or resumes the server. Nodes are processed one at a time, so only the server residing on the node being processed is affected, the servers on the other nodes continue to process work. Eventually all of the nodes and servers are updated.
The update process is complete when the updated version of the application is running on all of the LPARs in the cluster.
Related:
Application update procedure in a high availability environment High availability configuration Set up a highly available sysplex environment Stopping an application server to manually update a high availability application Pausing an application server listener to manually update a high availability application Update enterprise application files