Windows 10: GPT disk conversion for both data drives and C drive

Discus and support GPT disk conversion for both data drives and C drive in Windows 10 Drivers and Hardware to solve the problem; Newbie to the Windows 10 world. I just purchased a 6 TB drive, plugged it into my Windows 7 computer, and it worked fine for a system backup using... Discussion in 'Windows 10 Drivers and Hardware' started by HikerGuy, Apr 24, 2016.

  1. HikerGuy Win User

    GPT disk conversion for both data drives and C drive

    Newbie to the Windows 10 world.

    I just purchased a 6 TB drive, plugged it into my Windows 7 computer, and it worked fine for a system backup using Macrium prior to the Windows 10 conversion. Now am converted to Windows 10, and reading that I need the large drives converted to GPT from MBR.

    I have found reference to the AOMEI Partition Assistant to make this conversion on the data drive, but the C drive is a different animal.

    My understanding is that GPT is necessary for the large data drive, and only necessary for the GPT on the C drive if I migrate to UEFI.

    I have two questions:
    Is it necessary to have the 6 TB drive formatted in GPT, or does it solve any capacity issues I may have with MBR?
    To convert the C drive to GPT, what are the steps I need to take to make this work? Make a Macrium backup and rescue disk, save an image file, reformat C drive, and then reload the image onto C drive, now in GPT format?

    Would reloading an image onto a differently formatted C drive actually work? Or am I making this too complicated?

    HikerGuy, Apr 24, 2016

  2. Windows 10 update wont boot ,screen just flickers

    I would not leave that disk with the wrong formatting. Since you have room on the Samsung I'd move the data over and do one of the destructive reformats of the drive from

    Convert GPT Disk to MBR Disk - Windows 7 Forums

    Triple confirm all of the data made it over to the temp storage, and that you are choosing the correct drive (by size) before conversion.
    Greg Carmack - Windows MVP, Apr 24, 2016
  3. 'System Reserve' has appeared on my non-OS (secondary) hard drive after Windows 10 installation. How to delete?

    Hi Elliot -

    To move the Bootmgr to C, download and install
    EasyBCD (click Download - no Name or Email required)

    1) Choose BCD Backup/Repair Tab.

    2) Select Change boot drive

    3) Click button to Perform Action

    GPT disk conversion for both data drives and C drive [​IMG]

    In the popup confirm the New Boot Drive says C, click OK.

    GPT disk conversion for both data drives and C drive [​IMG]

    Reboot PC, confirm in Disk Mgmt that C is now marked System Active Boot. You can now delete System Reserved in Disk Mgmt, repartition the drive as a data drive. Since Windows can only recognize 2tb in the MBR disk format, I would convert the data drive
    to GPT before creating your data partitions.
    Convert MBR Disk to GPT Disk
    Greg Carmack - Windows MVP, Apr 24, 2016
  4. GPT disk conversion for both data drives and C drive

    The conventional wisdom is that converting MBR to GPT when C drive is involved, requires a reinstall. But this isnt true. You can 'convert' your MBR C drive to GPT but it's a bit complicated. I'm not familiar with Aomei, I would recommend using either DriveImageXML (free) or Drive Snapshot (free trial but needs a serial #) to back up C drive. Once backup is done, destroy the partitions and create a GPT partition table with whatever tool you like. I prefer using Gparted in Linux-based Partition Magic. Your first partition should be an EFI system partition (used for UEFI booting), format it as FAT32 and give it the 'boot/EFI/legacy boot' flags. This partition need not be any bigger than 512MB. Next create a partition for C, whatever size you like. Then create any other partitions you want.

    When done, boot into either a Windows-based rescue environment or Windows setup USB/DVD/etc. Now you will need GetWAIKTools, use it to download files necessary to create boot files for 10. Restore your backup image into the empty partition you designated for C drive. The partition needs to be at least as big as it was under MBR or it may not restore (i.e. if it's 100GB now then it needs to be at least that big before restoring).

    Last use bcdboot (that you got from GetWAIKTools) in a CMD (command) prompt to create boot files. Make sure your EFI partition is mounted to a drive letter first. This is where boot files will go.

    Example: bcdboot C:\Windows /l en-US /s A: /f UEFI

    A drive is the EFI partition.

    If you did everything correctly Windows should now boot in UEFI mode on GPT partitioning, and everything should be exactly as you left it before the backup. You can now create another backup once you've confirmed that everything works.

    Sorry if I was a bit vague, I'm in a rush today, and replied quickly, figuring that a quick response would be better than none. Just ask for clarification if needed. I've did this numerous times and it has worked most of the time.
    AnonVendetta, Apr 25, 2016
  5. HikerGuy Win User
    Anon, while I appreciate your response, you need to use smaller words.*Eek "A bit complicated" is an understatement.

    "It has worked most of the time." Now THAT is not a comforting statement to someone who is on Week #1 of Windows 10!!!!

    All joking aside, thank you for the informative response, as you are pointing out several areas I am clueless in, so will start getting up to speed on this as soon as possible. Be prepared for questions to follow.

    Seems like there are multiple points of potential failure that I could stumble into. FYI, my existing SSD C drive is only 512 GB, data drives are between 1 and 6 TB each.

    As the data drives are backups of each other, I could reformat a data drive using the method I was told about above. If it works, great, if it doesn't, I have multiple backups. So, if that is the first step, is it ok to have the data drives in a GPT format working with a C Drive in MBR format?

    Then I could concentrate on creating a rescue disk and reformatting the C drive, and making it bootable. At the moment, I am not comfortable not knowing what I don't know about this process, and need to get a better understanding before proceeding. Surely there is a Windows 10 Procedure for doing this somewhere?

    I am tempted to purchase a 2nd SSD and get it formatted correctly, and then do a windows install on that drive. Don't want to run into copyright issues and such as I am loading my programs onto the 2nd drive. Once done, I could reformat the original drive and use it for other purposes. Would this simplify things?

    Thx again
    HikerGuy, Apr 25, 2016
  6. HikerGuy Win User
    Here is another option question. Can I "clone" a MBR drive as a GPT drive, making the format change during the cloning process? If so, that would be the absolute easiest way (for me).
    HikerGuy, Apr 25, 2016
  7. HikerGuy Win User
    Until I started this thread today, I was totally oblivious to options. After just a bit of education (a dangerous thing in itself), I am leaning toward purchasing a newer SSD and cloning to that drive in GPT mode. That would free up my "old" SSD to be my intermediary between the C drive and my data drives. Doesn't seem terribly complicated this way, either.
    HikerGuy, Apr 25, 2016
  8. topgundcp Win User

    GPT disk conversion for both data drives and C drive

    Macrium Rescue disk can be used to convert from MBR to GPT and vice versa without doing a fresh install of Windows.

    • Download Rescue6.1.1081X64.iso - Google Drive and use Rufus to create a bootable USB disk. Skip this step if you've already created the Macrium Rescue disk.
    • Download: - Google Drive . Unzip to an external or an internal HD
      This is a copy of the first 3 partitions of my current Windows 10 x64 (450MB Recovery, 100MB EFI and 16MB MSR)
    • Boot up Macrium Rescue disk and create a backup of your current Windows to another internal/external HD. It serves 2 purposes: you'd have a backup of your current Windows in case things go wrong and then use it to restore the C drive on the next steps.
    • Next, switch the BIOS to UEFI and use Macrium to restore the first 3 partitions downloaded in step 2 to your current MBR Windows. No need to convert or Format, Macrium will do it.
    • Again with Macrium, select the backup image from step 3, and copy back the C drive after the 3 partitions.
      After this step, you should have: 450MB, 100MB, 16MB and C drive (GPT partition scheme)
    • From Macrium, click on Fix the Windows Boot Problems
    • Reboot. Your Windows should be in UEFI mode.
    topgundcp, Apr 25, 2016
  9. HikerGuy Win User

    Thank you for that alternative. Used Macrium for my backup prior to going to Win 10, almost foolproof. I will test the "almost foolproof" part by doing this formatting conversion.

    Your Rescue ISO. What exactly is that? A current or semi-current ISO for Windows 10 Pro? Is there any advantage to using that over the Macrium Rescue Disk?

    I think I am following your steps. Please see if the following is correct.

    Your BootEFI only file is a "copy of the first 3 partitions of my current Windows 10 x64". I have not partitioned drives before, and need to get educated on this. My assumption is that I would be putting 3 partitions on my hard drive because that is what your BootEFI copy is set up for, or are 3 partitions necessary for GPT setup? What are the 3 partitions reserved for?

    When I reboot into the BIOS and change to UEFI, that is when I need the Macrium Rescue Disk to boot into. That will have the Macrium program on it to restore the first 3 partitions onto my C drive, which then will have no programs, only 3 partitions.

    Then I would copy my C drive backup material "after the 3 partitions", fix windows boot problems, and then reboot to the drive.

    As you have a procedure already setup for this, you have obviously helped others do the same. At what points do people tend to make errors that causes crashes, formatting problems, etc.?

    No need to wait until I get a second SSD and load everything on that SSD, but that couldn't hurt anything, could it?
    HikerGuy, Apr 25, 2016
  10. topgundcp Win User
    It is a Macrium Rescue ISO in case people don't have Macrium installed to create it.
    You don't need to partition . Set the BIOS to UEFI then boot up the Macrium rescue disk, select the .mrimg file in step 2 as Source and select the disk you want to copy as Destination. Macrium will do the rest ie. initialize the disk as GPT and restore the first 3 partitions. Next, select the backup image that you have the C partition and copy it next to the 1st 3 partitions.

    On a fresh install of Windows 10 with GPT disk, there should be 4 partitions created:
    • 450 MB Resered partition contaning WinRE.wim (set of diagnostic tools used for trouble shooting Windows
    • 100MB EFI System partition containing Boot Code. Without it, Windows won't boot.
    • 16MB MSR partition (Microsoft Resered partition)
    • C drive.
    True. You can restore to your current SSD that is currently having MBR partition scheme and since you set the BIOS to UEFI, Macrium will restore as GPT type, it should work. In case things go wrong, you can always set the BIOS back to Legacy and restore your backup image with Macrium.
    topgundcp, Apr 25, 2016
  11. Superfly Win User
    I'm no expert at this but why have C >2GB? It's a windows only partition right?
    Overall 3 x 2 GB partitions should be OK for backups and saving data, not so? Just trying to figure why the need for GPT.
    Superfly, Apr 25, 2016
  12. NavyLCDR New Member
    I'm fairly certain you meant to be speaking about TB instead of GB GPT disk conversion for both data drives and C drive :). Unless you have some great trick up your sleeve, which I would love to see!
    NavyLCDR, Apr 26, 2016
  13. GPT disk conversion for both data drives and C drive

    @ HikerGuy: I lost track of this topic for awhile until I checked my Gmail and noticed multiple responses in this thread. I still think you should use the method I outlined instead of taking the easy way out. It can't hurt, you'll learn something, and you have multiple backups anyway, so nothing is lost. I can go into more detail if you wish.

    I'm sure the methods these other guys are talking about will work, but I've never used them. I'm a very technical person and tend to use tools that most people wouldn't mess with. I loath the point and click approach, letting some software do the work for me without giving me a precise explanation of exactly what is happening, where, and why. The only way to truly know how PCs really work is to get down and dirty do the hard work. It gives you a better understanding of how to fix issues when they occur. I understand if you just want to get it over with as painlessly as possible.

    When I say it worked most of the time, well, all PCs are different, and what works here may or may not work there. I have no formal education in computer science, etc, I'm just a self-taught hobbyist that does what I do for fun and entertainment, a learning experience, as well as necessity/wants. I'm 32 now and have been working with computers since I was 6 years old.
    AnonVendetta, Apr 5, 2018

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