High availability configuration
The objective of any high availability configuration is
to eliminate all single points of failure (SPOFs).
Stopping an application server to manually update a high availability application
For manual application rollout, workload routing is controlled
by stopping the application server on which the cluster member being
updated resides. This results in a quiesce of that server. All existing
requests already in the server are allowed to complete, but no new
requests are accepted. Both the sysplex distributor and the WebSphere® Application Server web server
plug-in routes work away from the quiescing server. After all work
has completed, you start the application update process on this server.
Automatically rolling out updates to a high availability application
You can set up your system to perform automatic application
rollout for your high availability applications. The automatic application
rollout update process stops or pauses each application server that
is hosting a cluster member that needs updating.
Pausing an application server listener to manually update a high availability application
Instead of stopping the application server, you can use
the MVS™ console Modify command to pause the listeners
for that application server, perform the application update, and then
resume the listeners. If you use this technique, you do not have to
stop and then start the server to perform the application update.