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MBR disk restore to UEFI system displays warning:
OS disk in backup uses MBR disk

KB ID: 3156
Product: Veeam Agent for Microsoft Windows
Version: 2.x, 3.x, 4.x
Published: 2020-04-27
Last Modified: 2021-03-08

Challenge

When attempting to restore a Windows machine using Bare Metal Recovery, the restore displays a warning stating the following:

OS disk in backup uses MBR disk. This may cause boot issues on UEFI systems
3156errorimage

Cause

The Bare Metal Recovery restore has detected that the system within the selected restore point was using MBR at time of backup, and the system that the restore is being ran on has been booted with UEFI BIOS.

Solution

Change BIOS settings from UEFI to Legacy Mode

If your machine supports the legacy BIOS mode, use the legacy BIOS mode instead of the UEFI mode. 

If you machine does not support the legacy BIOS mode, the steps below will provide instructions on how to restore the MBR based backup to a UEFI system.

  1. Boot from the Veeam Recovery Media.
  2. Go to Tools and start the Command Prompt utility.
  3. Run the following commands one by one:
    diskpart
    DISKPART> list disk
    
    At this step, find the disk that you are going to use as a restore destination for the primary operating system. In this example, we assume that disk 0 is a restore destination for the primary operating system.
    DISKPART> select disk 0
    
    Mind that the following command will remove all data from the disk 0.
    DISKPART> clean 
    DISKPART> convert gpt
    DISKPART> create partition efi size=200
    DISKPART> select partition 1
    DISKPART> format quick fs=fat32 label="System"
    DISKPART> assign letter=G
    DISKPART> create partition msr size=128
    DISKPART> exit
    
  4. Start the Bare Metal Recovery process, note that you will still see the "OS disk in backup uses MBR disk" warning during the restore process. On the "Restore Mode" tab choose [Manual restore (advanced)]. Do not restore the system partition and do not delete the partitions created at the previous step.
    You may have to manualy configure the disk layout. Simply restore the OS volume from the backup to the free space on the destination disk.
  5. After the restore process completes, do not reboot the machine.
  6. Go to Tools > Command Prompt utility and run the following commands: 
    Note: The drive letter G: is used in this example as it was the drive letter created in the Diskpart example above. If you used a different letter, please adjust the command accordingly.
    It advisable to using the "list vol" command within diskpart to check which drive letters were assigned to each volume.
    mkdir G:\EFI\Microsoft\Boot
    xcopy /s C:\Windows\Boot\EFI\*.* G:\EFI\Microsoft\Boot
    G:
    cd G:\EFI\Microsoft\Boot
    bootrec /rebuildbcd
    

More information

To learn about restoring a GPT disk to the incompatible legacy BIOS system, see this Veeam KB article.
KB ID: 3156
Product: Veeam Agent for Microsoft Windows
Version: 2.x, 3.x, 4.x
Published: 2020-04-27
Last Modified: 2021-03-08

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