Hello
The MBR2GPT tool is not available in Windows Server 2012 R2 Datacenter. This tool was introduced in Windows 10 version 1703 and is not backported to earlier versions of Windows, including Windows Server 2012 R2.
If you’re trying to convert a disk from MBR to GPT without losing data, you might want to consider using a third-party tool. One such tool is NIUBI Partition Editor. It allows you to convert an MBR disk to GPT without losing data.
Before starting, make sure the MBR disk that you want to convert is a data disk or system disk, because the method is different. If there’s only data on the MBR disk, it is extremely easy and fast to convert it to GPT without losing data, only several clicks are needed.
If there’s an operating system on the MBR disk, it’s a bit more complicated, because all system files must remain intact and the OS must boot correctly after converting to GPT. There are some third-party software that claim to be able to convert an MBR disk to GPT with an operating system on it, but few can ensure 100% system bootable.
Windows Server 2012 R2 convert MBR to GPT without losing data. (hdd-tool.com)