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Knowledge Base > Operating Systems > Windows > Vista/Win7/8.x/10 > Converting a GPT Data or Windows Disk to MBR/EMBR

Converting a GPT Data or Windows Disk to MBR/EMBR

Introduction

This article provides methods to convert GPT drives (both data and Windows 7/8.x/10) to MBR or EMBR. The conversion can be helpful in cases where booting needs to be changed to Legacy (non-UEFI) mode. An example would be that you wish to install BootIt Bare Metal and set up multi-booting on the system.

If you have TeraByte OS Deployment Tool Suite Pro (TBOSDT) for BootIt (included with the purchase of BootIt Bare Metal) you can use the chgdtype.tbs script to perform the conversion. For details, refer to the following KB article: Convert a Disk from GPT to MBR or MBR to GPT Using the chgdtype.tbs Script

Before you begin

  • Create your BootIt Bare Metal (BootIt BM) boot media. BootIt BM will be used to convert the driveís partitioning scheme from GPT to MBR/EMBR.

  • Have your Windows repair media ready if converting a drive containing Windows 7/8.x/10. You should use 32-bit (x86) repair media for 32-bit Windows and 64-bit (x64) repair media for 64-bit Windows.

    For a Windows 7 drive, the repair media can be one of the following:

    • Windows 7 installation DVD or USB flash drive (UFD)
    • Windows 7 Repair Disc or UFD
    • TBWinRE CD or UFD (created in Windows 7)
    • TBWinPE CD or UFD (created using the Windows 7 AIK)

    For a Windows 8/8.1 drive, the repair media can be one of the following:

    • Windows 8/8.1 installation DVD or USB flash drive (UFD)
    • Windows 8/8.1 Repair Disc or Recovery UFD
    • TBWinRE CD or UFD (created in Windows 8/8.1)
    • TBWinPE CD or UFD (created using the Windows 8/8.1 ADK)

    For a Windows 10 drive, the repair media can be one of the following:

    • Windows 10 installation DVD or USB flash drive (UFD)
    • Windows 10 Repair Disc or Recovery UFD
    • TBWinRE CD or UFD (created in Windows 10)
    • TBWinPE CD or UFD (created using the Windows 10 ADK)

Verify that the system being converted can successfully boot from the repair media. Do not skip this step unless you are certain booting to the repair media works correctly. Note: Some Windows systems will not properly create a bootable repair disc. In these cases, use a UFD or use TBWinRE/PE.

  • Create a backup image of the drive being converted (strongly recommended as conversion requires partitions to be deleted and modified).

  • Verify drive size. Drives larger than 2TB will normally be limited to 2TB when converted to MBR. Drives larger than 2TB may not be able to be converted depending on how they are partitioned.

  • If converting a Windows 7/8.x/10 drive, check the computer's BIOS and make sure it supports booting in Legacy BIOS mode (non-UEFI).

Converting a Data GPT drive to MBR/EMBR

This procedure is designed to convert a data GPT drive to an MBR drive. This type of drive does not contain a booting Windows installation.

  1. Boot into BootIt BM.

  2. Select Partition Work on the desktop (click the icon or tab to it and press Enter).

  3. Select the GPT drive to convert using the Drives drop-down box.

  4. Make note of the partition names and sizes (names/descriptions may be lost in the conversion and this will help you to know which is which).

  5. If converting to MBR you will need to have four or fewer partitions on the drive. Delete excess partitions as required. Note: This limit does not apply if converting the drive to EMBR.

  6. Click the Change Disk Type button and then click MBR (or EMBR, if using EMBR).

  7. Close the Work with Partitions window.

  8. Remove the BootIt BM media and reboot the computer.

Note: Drive letter assignments may need to be updated after booting into Windows.

Converting a Booting Windows 7/8.x/10 GPT drive to MBR/EMBR

This procedure is designed to convert a bootable GPT/EFI installation of Windows 7/8.x/10 to an MBR/EMBR drive. Be aware that some steps of the conversion vary depending on whether Windows was installed using the Microsoft media (standard installation) or if it's an OEM system (OEM installation).

The standard installation partition layouts differ slightly between the Windows versions:

  • Windows 7
    Partition 1: EFI System, 100MB
    Partition 2: Microsoft reserved partition, 128MB (not visible in Windows Disk Management)
    Partition 3: Windows 7 (size depends on drive)

  • Windows 8
    Partition 1: Recovery, 350MB - (WinRE)
    Partition 2: EFI System, 100MB
    Partition 3: Microsoft reserved partition, 128MB (not visible in Windows Disk Management)
    Partition 4: Windows 8 (size depends on drive)

  • Windows 10
    Partition 1: Recovery, 450MB - (WinRE)
    Partition 2: EFI System, 100MB
    Partition 3: Microsoft reserved partition, 16MB (not visible in Windows Disk Management)
    Partition 4: Windows 10 (size depends on drive)

OEM installations of Windows (those on brand-name/retail computers) usually include additional partitions, depending on how the manufacturer configured the system. For example, in addition to the standard partitions shown above there may an OEM partition, Data partition, and a second Recovery partition:

  • OEM Windows 8
    Partition 1: Recovery, 1000MB - (WinRE)
    Partition 2: EFI System, 260MB
    Partition 3: OEM, 1000MB
    Partition 4: Microsoft reserved partition, 128MB (not visible in Windows Disk Management)
    Partition 5: Windows 8, 651GB
    Partition 6: Data, 25GB
    Partition 7: Recovery, 20GB - (OEM Recovery partition)

Note: Converting an OEM system may disable access to the OEM partition and recovery partition. If converting to MBR you may need to delete one or more of the additional partitions to get the count to four or less.

Instructions:

  1. Disable the Windows Recovery Environment (WinRE):
    In most cases, disabling WinRE before the conversion allows it to be easily enabled afterwards and, depending on the system, skipping this step may result in a non-functional WinRE after the conversion is completed. However, some OEM systems may not disable completely and error when enabling after the conversion. Due to the nature of WinRE and the multitude of system configurations there may be systems where WinRE requires repairs to function properly after the conversion.

    1. Boot into Windows.

    2. Open an Administrator Command Prompt:

      If using Windows 7: Click on the Start button, then All Programs, then Accessories. Right-click on the Command Prompt item and select Run as administrator from the pop-up menu. If a UAC prompt is displayed, click the Yes button.

      If using Windows 8.x/10: Press WinKey+X (or right-click the lower-left corner of the Desktop) and click Command Prompt (Admin) on the pop-up menu. If a UAC prompt is displayed, click the Yes button.

    3. Run the following command:
      reagentc /disable

    4. Verify that winre.wim now exists in the C:\Windows\System32\Recovery folder. Run:
      dir /a C:\Windows\System32\Recovery

      For a standard installation of Windows you should see winre.wim in the list of files. For OEM installations it may or may not be there, depending on the configuration. If the file doesn't exist and you want to keep WinRE you can either keep the Recovery (WinRE) partition (don't delete it in Step 9) or go ahead and delete it and copy the winre.wim file from your backup image (if the winre.wim file can't be found you won't be able to enable WinRE after the conversion). Copying the file may require other modifications before WinRE can be enabled (see notes at end of article).

  2. Restart the computer and boot into the BIOS. Change the BIOS boot mode to allow booting Legacy mode (non-UEFI). Option specifics vary from system to system, but most have a setting to allow booting for Legacy BIOS, UEFI, or both. Some have an additional option for which mode gets priority. Itís recommended to give Legacy BIOS priority since that mode is required for the conversion boot repair and to boot the system after the conversion. Save the changes.

  3. Boot into BootIt BM.

  4. Select Partition Work on the desktop (click the icon or tab to it and press Enter).

  5. Select the GPT drive to convert using the Drives drop-down box. In most cases, this will be HD 0 (the booting drive).

  6. Make note of the partition names and sizes (names/descriptions may be lost in the conversion and this will help you to know which is which). A standard Windows 8 installation will be used as an example:

    • Recovery, 300MiB, NTFS - (WinRE)
    • EFI system partition, 100MiB, EFI System
    • Microsoft reserved partition, 128MiB, GPT Entry
    • Basic data partition, 122350MiB, NTFS (the Windows 8 partition)

  7. Select the EFI system partition. Click the Delete button. Select the Clear boot sector option and then click OK.

    Note: Clearing the boot sector is recommended. Otherwise, if a Windows boot repair is performed at a later time it may undelete the partition and complicate the repair.

  8. Select the Microsoft reserved partition. Click the Delete button. Click OK.

  9. If deleting the Recovery (WinRE) partition, select the Recovery partition. Click the Delete button. Click OK.

    Note: On OEM systems there may be more than one "Recovery" partition (e.g. one partition with WinRE and one with the OEM Recovery files). Also, per Step 1d, don't delete the Recovery (WinRE) partition if keeping it to retain the winre.wim file.

  10. If converting to MBR you will need to have four or fewer partitions on the drive. In the case of a standard Windows installation this isnít a problem (as above, you would only have one partition remaining). For the example OEM Windows 8 system shown above, you would probably want to delete partitions 2, 3, 4, 7, and (optionally) 1.

    Delete excess partitions as required to get the total to four or less. Note: This limit does not apply if converting the drive to EMBR (e.g. you plan on installing BootIt BM).

  11. Click the Change Disk Type button and then click MBR (or EMBR, if using EMBR).

  12. Partition names/descriptions may be lost at this point. You may find it easier to rename them back to their original names (as previously noted). Do this by selecting the partition and clicking the Properties button. Then edit the Label and click OK.

  13. Next, if you wish, you may slide and resize the Windows partition to use the unallocated space created by deleting the partitions.

  14. Set the Windows partition active:

    • Click the View MBR button.

    • EMBR Only: Use the Insert button to fill the partition table with the desired partitions. At the very least, the table must contain the Windows partition.

    • Select the Windows partition.

    • Click the Set Active button.

    • Click the Apply button.

  15. Close the Work with Partitions window.

  16. Insert the Windows repair media and reboot the computer into it. Note: The Windows repair media should be booted as a Legacy drive (not UEFI).

  17. Open a Command Prompt:

    If using the Windows installation media: Press Shift-F10 to open the Command Prompt.

    If using the Windows 7 Repair media: Select your language and keyboard (if prompted). A scan will be performed to find Windows installations. It will report problems found and offer to repair them. Click the No button to abort the auto-repair. Select the Use recovery tools... option and click Next. Click Command Prompt.

    If using Windows 8.x/10 Repair/Recovery media: Select your language, click Troubleshoot, click Advanced options, click Command Prompt.

    If using TBWinRE/PE: The Command Prompt can be started from TBLauncher.

  18. Find the drive letter assigned to the Windows partition. This should normally be C: since the Windows partition is set active and it's on the booting drive. Using the prompt, you can run dir c:, dir d:, etc. until you locate the correct partition. If youíre using TBWinRE/PE you can click on TBLauncher and press F4 to see a list of drive letter assignments. C: will be used for the Windows partition in these instructions Ė make sure to substitute the drive letter appropriate for your system.

  19. The next step is to configure the BCD file on the Windows partition. Standard installations of Windows (those from the Microsoft media) don't include the \Boot folder or BCD on the Windows partition. However, OEM installations of Windows may include them and have it preconfigured to boot into Windows. You can determine if they exist by running the following command:
    dir /a C:\Boot\BCD

    The output will show the BCD file if it exists or a "File Not Found" message if it doesn't. If the BCD file exists you have the choice of using it or deleting it and recreating a new one. Creating a new one is recommended since the existing file may prevent WinRE from functioning fully.

    To delete an existing \Boot folder and BCD file, run the following command:
    rd /s /q C:\Boot

    To rebuild/create the Windows BCD, run the following command:
    bcdboot C:\Windows /S C:

    Note: On Windows 8.x/10 systems, if the computer isn't properly booted in Legacy BIOS mode you can force the Legacy BIOS booting files to be used by specifying the /F BIOS option when you run bcdboot. This usually is not necessary.
    bcdboot C:\Windows /S C: /F BIOS

  20. Copy the bootmgr file to the Windows partition by running the following command:
    copy C:\Windows\Boot\PCAT\bootmgr C:\

    Note: This step can normally be skipped on Windows 8.x/10 systems since the file should already exist on the Windows partition. You can verify it exists by running the following command and finding it in the listing:
    dir /a C:\

  21. Close the Command Prompt window and remove the repair media.

  22. Reboot the computer.

  23. Windows should boot up normally.

    Note: If Windows doesn't boot up successfully, verify that the Windows partition is set active, the BCD file exists, and bootmgr exists. If necessary, boot to the Windows repair media and do a Startup Repair (you may be prompted to run it after booting if a problem is detected).

  24. Enable the Windows Recovery Environment (WinRE):

    1. Open an Administrator Command Prompt.

    2. Run the following command:
      reagentc /enable

      Note: If there is an error enabling WinRE see the notes at the end of the article.

  25. The conversion is complete. If desired, you can now proceed with installing BootIt BM. If you had previously enabled TBWinRE on the system it may now be disabled. Run TBWinRE again, if necessary.

 


Notes:

Restoring Backup of Drive Created Prior to Conversion

If you restore the backup of the drive you created before the conversion and intend to boot it, you will need to enter the BIOS and enable support for UEFI booting. Otherwise, the drive will fail to boot.

WinRE Fails to Enable After Conversion

Enabling WinRE can fail for a number of reasons, including:

  • The winre.wim file is missing or not at an expected location.
  • WinRE only partially disabled or enabled.
  • The configuration file (ReAgent.xml) contains invalid information.

The following repair methods can be used before trying again to enable WinRE (Step 24, above):

  • Sometimes all that's needed is to disable WinRE prior to enabling. Run the following commands at an Administrator Command Prompt:
    reagentc /disable
    reagentc /enable

  • Make sure the winre.wim file exists in the original path (e.g. on the existing Recovery partition) or in the C:\Windows\System32\Recovery folder. Note that the file may be hidden (enable viewing of hidden/system files, if necessary). If the file is missing you can copy it out of the backup image using TBIView or TBIMount.

    You can determine if the original path is still being used by viewing the ReAgent.xml file and checking the path for the ImageLocation. The ReAgent.xml file is located in the C:\Windows\System32\Recovery folder and can be opened using Internet Explorer, Notepad, or WordPad. If using Notepad you will most likely want to enable word wrapping for easier viewing. Look for <ImageLocation path= and note the path value specified (e.g. <ImageLocation path="\Recovery\WindowsRE"). If the original Recovery partition is no longer available you can create the path on the Windows partition and copy the winre.wim file into it. Then try enabling WinRE. In this example, you would copy winre.wim into the C:\Recovery\WindowsRE folder.

  • If neither of the above methods worked you can try resetting sections of the ReAgent.xml file.

    Note: On Windows 8.x/10 systems you can try removing the ReAgent.xml file instead of editing it. It should be recreated when you run the command to enable WinRE. For example, you could rename ReAgent.xml to ReAgent_backup.xml before trying to enable WinRE.

    This example will use WordPad to edit the file. Start an Administrator Command prompt and run the following command:
    write c:\windows\system32\reagent.xml

    Edit these sections to clear/reset the values: WinreBCD, WinreLocation, ImageLocation, InstallState, WinREStaged. Leave other sections and settings unchanged. The example below is from an OEM Windows 8 installation (your file contents may be different). The indicated sections are shown with cleared/reset values.

    <?xml version='1.0' encoding='utf-8'?>
    <WindowsRE version="1.0">

      <WinreBCD id="{00000000-0000-0000-0000-000000000000}"/>
      <WinreLocation path="" id="0" offset="0" guid="{00000000-0000-0000-0000-000000000000}"/>
      <ImageLocation path="" id="0" offset="0" guid="{00000000-0000-0000-0000-000000000000}"/>

      <OsInstallLocation path="\OKRbackup\factory\" id="0" offset="728680628224" guid="{f0ea3b1a-8657-4f56-abd1-dfea687a2d2f}" index="1"/>
      <CustomImageLocation path="" id="0" offset="0" guid="{00000000-0000-0000-0000-000000000000}" index="0"/>

      <InstallState state="0"/>
      <OsInstallAvailable state="1"/>
      <CustomImageAvailable state="0"/>
      <IsAutoRepairOn state="0"/>

      <WinREStaged state="0"/>
      <OperationParam path=""/>
      <OsBuildVersion path="9200.16384.amd64fre.win8_rtm.120725-1247"/>
      <OemTool state="1"/>
      <BootKey state="0"/>
      <IsServer state="0"/>
      <ScheduledOperation state="4"/>
    </WindowsRE>


    Save the file and close WordPad. Make sure the winre.wim file is in the C:\Windows\System32\Recovery folder. Then try enabling WinRE.

 


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