Companies planning to upgrade from Hyper-V Windows Server 2012 R2 to the next version (probably Hyper-V Windows Server 10) should consider the issue of migrating virtual machines to the new version. The next version of Hyper-V will include a progressive upgrade feature that will allow administrators to upgrade existing Hyper-V cluster nodes one after another without having to disconnect the cluster.
Despite this possibility, administrators will need to consider how to migrate VMs to the new version of Hyper-V.
Whether or not the enterprise is running a clustered Hyper-V deployment, dynamic migration of a VM from an existing Hyper-V server to a next-generation Hyper-V server is possible. But above all, dynamic migration is not necessarily a definitive operation. The administrator has the option to reverse the dynamic migration of the VM to the existing Hyper-V server until it has updated the VM version, as this operation only makes it compatible with the VM. latest version of Hyper-V.
As was the case with previous versions of Hyper-V, the host server must be configured to send and receive dynamic VM migrations.
The example below shows how it works. I used the Get-VM PowerShell cmdlet to retrieve the version number of a VM running on a Windows Server 2012 R2 Hyper-V server. As shown in the figure, the version number is 5.0. The PowerShell command I’m using is:
Get-VM <VM name> | Select-Object Name, Version
You can use the Get-VM cmdlet to retrieve the version number of a VM.
The dynamic migration process works in exactly the same way as in Windows Server 2012 R2 Hyper-V.
Even a dynamic migration launched from an existing Hyper-V server can migrate a VM to a new generation Hyper-V server.
In the following image, you can see the existing VM after it has been dynamically migrated to the Hyper-V “Windows Server 10” server. But most importantly, you can see that the VM has kept its version number despite the fact that it runs on a hypervisor newer than the one on which it was created.
Since the VM has kept its version number, it can be migrated dynamically to a Hyper-V server without any problem. Dynamic migration to an existing Hyper-V server becomes impossible only after upgrading the VM to version 6.
Which brings me to another interesting point: I mentioned above that the new version of Hyper-V will feature a progressive upgrade feature that allows cluster nodes to be upgraded one by one. If a VM is running on a cluster of new and existing versions of Hyper-V, you will not be able to upgrade its version until all nodes in the cluster run the new version of Hyper-V. V.
Hence the question, of course, whether the upgrade of a VM has any advantage, especially since its previous version can not be restored. Well, upgrading a VM to version 6 will take advantage of the new features of Hyper-V and the new format of the configuration file. For example, Version 5 VMs continue to behave as if they were running on an existing version of Hyper-V. New features and capabilities are only available to VMs that have been upgraded.
In addition, upgrading a VM to version 6 is a simple task. To do this, enter the following command in PowerShell:
Update-VMConfigurationVersion <VM name>
After entering this command, you will receive a warning informing you that you will not be able to migrate the VM or import it into a host that is running an older version of Hyper-V. Figure D shows the command.
As you can see, it is easy to migrate a VM to a Hyper-V “Windows Server 10” server. This VM can be migrated dynamically back to an existing Hyper-V server as long as it has not been upgraded.