With Windows Server 2008 and 2008 R2 end of support on Jan. 14, 2020, virtualization administrators must come up with a plan for their Windows Server 2008 VMs. Unfortunately, continuing to run Windows Server 2008 or 2008 R2 on VMs isn’t a viable option. Although the OSes will continue to function after Windows Server 2008 end of life, Microsoft will no longer provide security updates, leaving VMs vulnerable.
If admins want to keep their VMs running on premises, then their best option is to upgrade to a newer OS. When it comes to OS upgrades, Microsoft generally recommends that admins create a new VM that runs the new OS, and then migrate their workloads from the old VM to the new VM. This approach helps to ensure security and stability because the workload is running on top of an OS that admins cleanly install. Transitioning workloads to a new VM also gives admins the option of using a different storage configuration or adopting the Resilient File System.
It’s sometimes necessary to perform an in-place OS upgrade on an existing VM, rather than creating a new VM and migrating the workloads. This is especially true when an application that is running on a legacy VM can’t be easily reinstalled on a new VM. For example, admins might require an in-place upgrade if they no longer have access to an application’s installation files or if they used up all of the application’s license activations.
If admins decide to perform an in-place upgrade, then their upgrade path might vary depending on the version of Windows Server they adopt. For example, admins can’t upgrade directly from Windows Server 2008 to Windows Server 2016. However, admins can upgrade to Windows Server 2012 R2 and then to Windows Server 2016.
Admins also can’t change system architectures such as 32-bit and 64-bit during an in-place upgrade, nor can they change the OS’s language.
Admins should understand that Microsoft removed the option to switch from Server Core to the full GUI experience in Windows Server 2016. This means that if a VM is currently running Server Core and admins want to switch to GUI mode — or the other way around — they must upgrade the VM to Windows Server 2012 R2, switch to the mode they want to use and then continue on with an upgrade to Windows Server 2016 or later.