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Cluster-Aware-Updating

Some admins prefer the Cluster updates to be done automatically. To do so, Microsoft designed a feature to facilitate patching of Windows Servers from 2012 to 2016 that are configured in a failover cluster. Cluster Aware Updating (CAU) does this automatically, thereby avoiding service disruption for clustered roles.

In this article, we are going to take a look into how we can achieve this assuming that Cluster is built with hyperconverged scenario and StarWind Virtual SAN used as a shared storage. Before going in the steps to set the CAU, we will investigate this scenario.

Let’s say you have activated automatic updates. One day they were downloaded and installed. Then, you restart one host, but StarWind VSAN does not complete the synchronization process to the restarted host when you initiated restart of another one. What happens next? All devices will become not synchronized and production will be interrupted. Due to such scenarios we have come up with a pre-update script you can configure within CAU.

In general, this script scans the devices on both nodes by checking the synchronization status. If devices are synchronized in both hosts, the restart of the host will proceed. In case of any devices are still synchronizing, it will postpone the restart till the synchronization is completed.

Getting to the interesting part for configuration, we have two scripts that we use. The first one is Runner_cau.ps1 that runs the main script with –STA parameter and it should be configured in Cluster self-updating options. The second script CAU.ps1 is the main script that does the process of checking the devices synchronization status. These scripts are both located in one of your Cluster Shared Volumes.

Here are the examples of the scripts which have been already mentioned:

Runner_CAU.ps1 script:

CAU.ps1

Before jumping into the next steps, let’s take a look at CAU.ps1 script and small changes that need to be done. As you can see below, the IPs need to be changed according to your environment. Also, in the same script, you can find several commented lines which you can use for troubleshooting or, alternatively, for log generation.

StarWind Virtual SAN eliminates any need for physical shared storage just by mirroring internal flash and storage resources between hypervisor servers. Furthermore, the solution can be run on the off-the-shelf hardware. Such design allows StarWind Virtual SAN to not only achieve high performance and efficient hardware utilization but also reduce operational and capital expenses.

Learn more about ➡ StarWind Virtual SAN.

PowerShell window with a script.

Below are the steps that we need to take to configure CAU successfully:

1. Open Failover Cluster Manager, select your cluster as shown in the screenshot and click on Cluster-Aware-Updating.

Failover Cluster Manager

2. On the next window, click Configure cluster-self-updating options.

CAU window

3. Click next on the Getting Started window.

Getting started window

4. On Enable self-updating mode, select Enable self-updating mode and click next.

Enable self-updating mode

5. The next window has to do with the scheduling. Select the frequency for the updates and click Next.

Self-updating schedule

6. In the Advance Option window, we need to include the path where the runner script is located, in this case, it was on volume1. This can differ in your environment, so please make sure you have the correct path.

Advanced Options

7. If you would like to receive the updates, choose the corresponding option in the Additional Update Options window.

Additional Options

8. Confirm the details and click Apply.

Confirmation

Completion9. We have successfully added the role.

Conclusion

As you can see, you are set for automated updates in a quite simple way. Well, you can go ahead and set this up in your environment and let me know in the comments about your experience!

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Paulsen Muzari
Paulsen Muzari
Paulsen is a Post-Sales Support Engineer. Well experienced in storage systems, virtualization and infrastructure implementation. Rugby and gaming as a hobby