Restoring a GPT System Image to an MBR Disk

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- What are MBR and GPT?

- Is My Operating System Disk MBR or GPT?

- Restoring a GPT System Image to an MBR Disk

- Prepare the Destination Disk

- Restore the GPT System Image to the MBR Disk

- Run 'Fix Windows Boot Problems'

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What are MBR and GPT?

Master Boot Record (MBR) and GUID Partition Table (GPT) are two different ways of storing partition and boot information on a disk and are closely coupled with the two different types of computer firmware: BIOS and UEFI.

BIOS, and by extension MBR disks, are now considered legacy and have largely been replaced by UEFI firmware and GPT disks. GPT disks, the newer of the two partitioning schemes, have several advantages over MBR disks. MBR disks are limited to having 4 primary partitions with a maximum disk size of 2.2TB, whereas GPT disks have a maximum number of 128 partitions with a theoretical maximum disk size of 18 EB (Exabytes). However, there are still some scenarios where an operating system that is stored on a GPT disk needs to be restored to an MBR disk, for example, when attempting to boot an operating system on legacy hardware.

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Is My Operating System Disk MBR or GPT?

The easiest way to tell whether an operating system disk is located on an MBR or GPT is to check the 'Create Backups' tab in Macrium Reflect or the Macrium Reflect rescue media.

First, determine which disk is the operating system disk; this is a disk that contains system partitions, partitions that are required by the operating system to boot and function correctly. System partitions are denoted by the Windows icon shown on the partition:

System Partition:

Non-System Partition:

Above the disk will be shown Disk X MBR or GPT, indicating the partition scheme that is being used for the disk:

GPT Initialized Disk:

MBR Initialized Disk:

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Restoring a GPT System Image to an MBR Disk

First, boot the system, where the restore will take place, with the Macrium Reflect rescue media. This article contains more information about creating the rescue media.

For the GPT to MBR system image restore to take place, the rescue media should be booted in legacy (CSM) mode. We recommend contacting the system or motherboard manufacturer for further assistance with changing boot modes.

To check that the rescue media has been booted in the correct mode, look at the top bezel within the rescue media. If the rescue media has been legacy booted correctly '[UEFI]' will not be shown on the top bezel, similar to the example below:

If '[UEFI]' is shown on the top bezel, then the rescue media has been booted in the incorrect mode for this restore. 

Prepare the Destination Disk

Next, the target disk should be prepared. This is done using the command-line diskpart utility. First, launch the command prompt using the command prompt icon on the rescue media taskbar:

In the window that opens, type 'diskpart' then press the 'Enter' key:

diskpart

In diskpart, you can view the disks that are connected to the system using the 'list disk' command. 

list disk

This will return a list of the disks that are currently connected to the system, similar to the example below:

Select the destination disk for the GPT to MBR restore using the 'select disk X' command, replacing X with the relevant disk number:

select disk 0

Remove any existing partitions and data from the disk with the clean command:

clean

Next, initialize the disk with the MBR partition scheme:

convert mbr

Next, the Microsoft System Reserved (MSR) partition should be created:

create par pri size=300

This partition should be formatted as NTFS:

format fs=ntfs quick

Finally, the partition should be marked as 'active', indicating that the operating system will boot from this partition.

active

Following this command, the disk is ready for the GPT to MBR restore. The command prompt should look similar to the example below:

Viewing the disk on the 'Create Backups' tab should look similar to the example below:

Restore the GPT System Image to the MBR Disk

Now that the disk has been correctly prepared, the GPT system image can be restored to the MBR disk. To do this, select the 'Existing Backups' tab, then select the 'Image' tab. If the GPT system image that will be restored is not shown in this tab, use 'Browse for an image file...' to open an Explorer window and select the image manually:

Next, select the GPT system image file that will be restored, then select 'Restore':

In the window that opens, click 'Select a disk to restore to...' and select the MBR disk that was prepared earlier:

Drag and drop the Windows partition from the source image to the destination disk, but do not copy the UEFI system partitions from the source disk:

Once partitions have been placed on the destination disk, they can be resized and floated as necessary to enable all partitions from the source disk to be copied and ensure that all unpartitioned space on the destination disk has been used. This article contains more information about modifying the partition properties while restoring. Once the partitions have been copied to the destination, select 'Next >' to proceed with the wizard.

The final page of the wizard contains a summary of the restore that is about to take place. Once the summary has been reviewed, select 'Finish' to start the restore.

Run 'Fix Windows Boot Problems'

Once the restore has been completed, run 'Fix Windows boot problems' on the 'Existing Backups' tab to create the new MBR boot configuration data:

This article contains more information about running 'Fix Windows boot problems'.

Once 'Fix Windows boot problems' has completed, restart the system and boot into the restore operating system.