The Windows Server has been using clustering as a way to update applications for many years. The reason for the cluster method is to ensure that servers and their applications are kept running during the process even if one part of the update should fail. These clusters include nodes and there are times when they fail but this method helps prevent an overall system failure. If you are new to this process, we are going to take a look at how it works and why so you can better understand the reasoning for the method.
Why is it Needed?
The cluster upgrades were first put into place to make sure that all Service Level Agreements were met while also making ure the high uptime requirements were met. During upgrades, cluster nodes are drained and rebalanced. Using a cluster to complete the task will make it more resilient to any errors. This results in the processes and services continuing no matter what happens during the cluster.
What is Different with Windows 2016?
Even with the cluster process, there was still one missing component: there was no way to upgrade the host operating systems. With the new Windows Server 2016, the cluster allows for a mixed OS mode. This ensures that an individual cluster can run both the Windowns Server 2012 and the 2016 version which can allow for an upgrade to the host operating system. The new process will drain cluster nodes and pgrade operating systems one at a time. Once all of the cluster nodes are at Windows Server 2016, a PowerShell cmdlet will update at the functional level.
How Does the Process Work?
During the clustering part of this process, a node is taken offline. While it is offline, it is upgraded. Once this is done, the node is added back and the process begines with the next node. This will continue until all of the clusters in the server are completed. You can even add a node temporarily of you cannot remove one. This process is best used when there are smaller clusters needing an upgrade.