You can perform a rolling upgrade of an application deployed to a single cluster, providing the cluster’s configuration is not shared with any other cluster.
Save an old version of the application or back up the domain.
To back up the domain use the asadmin backup-domain command.
Turn off dynamic reconfiguration (if enabled) for the cluster.
To do this with Admin Console:
Expand the Configurations node.
Click the name of the cluster’s configuration.
On the Configuration System Properties page, uncheck the Dynamic Reconfiguration Enabled box.
Alternatively, use this command:
asadmin set --user user --passwordfile password-file cluster-name-config.dynamic-reconfiguration-enabled=false
Redeploy the upgraded application to the target domain.
If you redeploy using the Admin Console, the domain is automatically the target. If you use asadmin, specify the target domain. Because dynamic reconfiguration is disabled, the old application continues to run on the cluster.
Enable the redeployed application for the instances using asadmin enable-http-lb-application.
Quiesce one server instance in the cluster from the load balancer.
Follow these steps:
Disable the server instance using asadmin disable-http-lb-server.
Export the load balancer configuration file using asadmin export-http-lb-config.
Copy the exported configuration file to the web server instance’s configuration directory.
For example, for Sun Java System Web Server, the location is web-server-install-dir/https-host-name/config/loadbalancer.xml. To ensure that the load balancer loads the new configuration file, be sure that dynamic reconfiguration is enabled by setting the reloadinterval in the load balancer configuration.
Wait until the timeout has expired.
Monitor the load balancer’s log file to make sure the instance is offline. If users see a retry URL, skip the quiescing period and restart the server immediately.
Restart the disabled server instance while the other instances in the cluster are still running.
Restarting causes the server to synchronize with the domain and update the application.
Test the application on the restarted server to make sure it runs correctly.
Re-enable the server instance in load balancer.
Follow these steps:
Repeat steps 5 through 8 for each instance in the cluster.
When all server instances have the new application and are running, you can enable dynamic reconfiguration for the cluster again.