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I am planning on migrating from my current ESXi environment to HyperV. I have two standalone servers (Hyperv1 and Hyperv2) with no shared storage, all vms are on the local servers. Hyperv1 has a primary AD/DHCP/DNS VM and Hyperv2 has a secondary AD/DHCP/DNS VM so that these services are still up if either of these servers goes down for maintenance. I don't host any servers that need to be up after hours, so every day I could have them down if needed after 4pm to 6am daily.
I need to know if I can install updates on Hyperv1 host while the vms are running and only save/suspend/shutdown the vms when the Hyperv1 host needs to restart to complete updates, or do I need to shutdown all vms daily before Hyperv1 is scheduled to install updates, even if those updates don't require Hyperv1 to restart after they are done. I need to know if the process of installing updates on the host can cause the hosted vms to lose network connection or cause issues with them, or if Windows will only update things needed for running HyperV vms during the host reboot process.
The way I see it, I have two options below, which I would much prefer to use Option 1, but need to know if it would cause issues.
Option 1 Basically, can I set Hyperv1 to automatically check for and install updates and reboot when needed after hours, and set the VMS to automatically save/suspend on host shutdown and automatically boot on host startup.
Option 2 Set Hyperv1 to check for and download updates daily and only install updates at say 10pm and script the vms to shutdown before the scheduled install time, even if there are no updates to install on the host, and even if the installed updates on the host don't require a restart after being installed.
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The virtual machines are not affected by the host's patch process, only the shut down portion. Take option 1. There have been some cases when VMs don't shut down or don't start up properly, but do not attempt to solve that problem unless you discover that you have it.
Can either of you shed more light on this chat with ChatGPT on this subject.
You
It appears as if applying updates to the host can affect the running vms in this statement is that correct "Service and application interruptions: Some patches, particularly those related to core components like the .NET Framework, may require stopping certain services or applications on the VMs. This can lead to downtime for those services or applications even before the host reboots."
ChatGPT
Yes, that statement is correct. While Hyper-V itself tries to minimize the impact of host updates on running VMs, certain updates, especially those affecting core components like the .NET Framework, may still require stopping certain services or applications running within the VMs. This can lead to downtime for those services or applications even before the host reboots. It's important to be aware of these potential impacts when planning host updates and to have strategies in place to minimize disruptions to your services.
You
I thought that the host environment and the vm environment were totally isolated/separate, but you're telling me that they share services like .NET?
ChatGPT
The host environment and the VM environment are indeed isolated in many ways, but there are certain shared components or dependencies that can affect both. One example is the .NET Framework, which is a software framework developed by Microsoft that primarily runs on Windows.
In the context of Hyper-V, while the host and VMs are separate, if the host is updated with a new version of the .NET Framework or if there are changes to the underlying components that affect the .NET Framework, it can potentially impact the behavior of applications or services running inside the VMs that rely on that specific version of the .NET Framework. This is because the .NET Framework is a shared component that can affect the operation of applications across the host and VM boundaries.
It's important to understand these dependencies when managing and updating your Hyper-V environment to avoid potential issues with your VMs.
So it appears as if I would require Option 2 If this is correct Do you have any documentation on this, or any other explanation.
ChatGPT is very wrong. It looks like it is pulling information from separate sources and incorrectly blending them. You can stop any service in the management OS and Hyper-V guests will keep running, with the lone exception of the cluster service on a clustered Hyper-V system. Hyper-V cannot have a dependency on any of those services because Hyper-V starts before they do. Hyper-V starts, then it starts the management operating system (which is itself a special-case virtual machine), then it starts up the VMs if they are configured for auto-start. They do not share kernels or services or anything else. Your presumption that the management OS and each guest has completely separate operating environments is correct.
I don't know if there's any official document that spells this out, but I've been running Hyper-V in test since 2008 and in production since 2008 R2 and my patching practices depend on the VMs not being impacted by any portion of the management operating system patch cycle except the reboot.
The worst I've ever seen is that the host gracefully shuts down for patching but hard turns off some of the VMs.
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Hi Cheezle,
Thanks for your reply. It is recommended to set up an update (WSUS server) in the VMM fabric and configure update baselines. If you prefer to restart the computers manually after remediation completes, select Do not restart the servers after remediation. By default, the computer restarts if any updates require it. If you choose not to restart and updates need it, the computer status will be Pending Machine Reboot after the remediation. The updates won't be activated until you restart. With this status, VMM won't scan the machines for compliance during refreshes.
Reference: Update Hyper-V hosts and clusters | Microsoft Learn
Best Regards,
Ian Xue
If the Answer is helpful, please click "Accept Answer" and upvote it.
Hey,
As mentioned, yes you can install updates without any issue. You should select "Do not restart the servers after remediation" to reboot Hyper-V server manually.
Since you have 2 Hyper-V hosts, you can consider creating Failover Cluster, which will allow you to avoid downtime for your VMs. StarWind VSAN can be used as a shared storage. VSAN creates replicated storage on top of local, which can be used to create Failover Cluster. https://www.starwindsoftware.com/starwind-virtual-san
You can also configure cluster-aware updating to automate the process.
https://learn.microsoft.com/en-us/windows-server/failover-clustering/cluster-aware-updating
Cheers,
Alex Bykovskyi
StarWind Software
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