Deploying a Windows 7 image to a virtual machine is not as straightforward as you might think.
The primary issue resides in how the reference Windows 7 system is installed.
If you create a VM and insert your Windows 7 media and proceed to click Next through the entire installation wizard, you will have a working Windows 7 installation, that can be templated, it can be copied, you can do just about anything you like to it – as long as all copies involve the entire virtual disk.
Say that you want to use ImageX to image the Windows 7 installation and then deploy that Windows 7 image to other virtual systems.
If all that you did was click Next through the installation wizard or you did not customize your unattend.xml at all – you actually have a VM that has been installed with two volumes – a System Reserved volume and the volume where the actual system is installed.
The standard process is that you boot your system into the WinPE environment and you use ImageX /capture to create a WIM from a particular volume. Note the word “volume.” ImageX is a volume based tool, not a disk based tool.
The problem comes when we try to deploy this image. We boot into ImageX and /apply – then we reboot the virtual machine and we end up with the error: “BOOTMGR is missing”
The boot manager resides on the System Reserved volume, that is the extra partition that is created but was not captured by ImageX.
According to Microsoft TechNet documentation How to Perform Common Deployment Tasks with Virtual Hard Disks we need to use BCDBoot.exe to “configure the boot entry in the BCD store to be on the volume inside the VHD.” If you follow the link, the portion that we are concerned with is: “Prepare a VHD image to boot inside a virtual machine.”
To repair the VM where the image we need some type of recovery environment. We can get to a prompt to fix the applied image by any of the following ways: Boot to a WinPE 3.0 ISO, Boot to a Recovery Console using the OS installation media, attach the virtual disk to another known working Windows virtual machine.
For my example I have used the Windows Automated Installation Kit and created a WinPE 3 ISO. However, in testing I first simply attached the failing virtual disk to a working VM and performed the same commands. I also found references that booting into the Recovery Console of the installation media also works, but I did not test this. It is important to note that if you use WinPE the bit-ness of your WinPE image must match the bit-ness of the OS in the VM (32-bit to 32-bit / 64-bit to 64-bit).
The repair process:
1. Boot the virtual machine into WinPE (or attach the virtual disk to a running VM).
(An alternative to this is to boot using the installation media. At the "Install Windows" screen (the first screen of the installer) type Shift+F10 to open a command prompt)
2. Discover the drive letter assigned to the virtual disk that is failing to boot.
3. Execute the following command (pay attention to use the correct drive letter – in my example “C:” is the letter that was assigned to the virtual disk, the WinPE system volume is “X:”).
C:\windows\system32\bcdboot C:\windows /s C:
4. Simply type “exit” to cause WinPE to shutdown and reboot into the VM. If the virtual disk was mounted in another VM, then power off the VM and detach the virtual disk before booting the imported VM.