How to convert from GPT to MBR the drive hosting Windows 7 partition


  1. Posts : 2
    Windows 7 Ultimate x64
       #1

    How to convert from GPT to MBR the drive hosting Windows 7 partition


    Hi everyone.

    This is my first post in this forum and I am not sure of posting it in the correct section. If not, I kindly ask the moderators to bare with me a move it to the most suitable place.

    Also, I am conscious that I am asking a question that could have been already answered in one of the very many discussions in this forum, but although I have already searches within this site and intensively googled everywhere during the last 2 hours I could not retrieve anymore a Step-by-Step guide that I have found a couple of weeks ago when I had to manage this task a first time (and I did not, stupidly, keep note of the guide's link...).

    So, here is my issue: I have installed Win 7 Ultimate 64bit on a GPT partitioned SSD, but due to some troubles that I'm encountering when attempting to boot my system after adding some more disks with MBR partition scheme, I'd like to move the OS disk to MBR scheme too.

    I have already gone through this process a couple of weeks ago on another system that I have and that was affected by the same problem but, as I said before, I was quite stupid to forget taking diligently note of the instructions that I luckily found on the net at that time.

    I only remember that following such step-by-step guide, based on the use of several commands manually entered in "command prompt window" and on the manual copy of some files from one system partition to the one hosting the windows 7 system files, I finally managed to have my partition hosting the Windows 7 filesystem successfully booting after conversion of the disk to MBR leaving then the option to delete the (now useless) extra partition of the former GPT partition scheme and toe ability to ultimately resize the windows partition to the full available space.

    My unsuccessful memory effort to retrieve such instructions lead me only to a certainty: I did not make the process booting my computer from Linux and using Linux utilities for conversion to MBR and I even seem to remember that some of the steps to copy/move the boot files from the system partition to the windows partition have been made 'live' from a command prompt within the booted and active win 7 installation.

    Is there anyone who can help my poor memory with some links to that (or similar) guide for this conversion?

    Thanks very much to all for any possible help, and in particular for keeping reading patiently this long post.

    Marco
      My Computer

  2.    #2

    Make sure to get your BIOS settings correct if this is a UEFI BIOS. You'll want full Legacy BIOS, CSM fully enabled, no UEFI. If in doubt post back the choices offered. A camera snap is helpful.

    Then the easiset method is here to Bypass UEFI to Install WIn7 to an MBR disk.
      My Computer


  3. Posts : 2
    Windows 7 Ultimate x64
    Thread Starter
       #3

    Thanks for your kind attention and for your reply.

    maybe I was not clear enough in my previous post (sorry about that), but I indeed learned (after...) how to install windows 7 in UEFI or traditional way and even how I should configure eventually my bios setting.

    the issue is that I now have already a Win 7 installation on my GPT disk (by the way, after having also gone through the hundred of automatic updates, since my installation DVD was purchased prior to SP1...), and I want to avoid starting over from scratch with a new/fresh reinstallation of everything based on a freshly repartitioned disk with MBR table.

    So, I'm trying to retrieve a guide that I found two weeks ago (and, as I already said, I stupidly not save somewhere...) who drove me, step-by-step, to the conversion of my GPT-partitioned disk into a MBR one without the need of deleting any of the GPT partitions (the "System" and the OS filesystem one) in my disk, such conversion being made with no use of Linux utilities but simply with normal "DOS-windows-like" commands such as dispkart as well as disk utilities ran directly from the windows installation itself.

    I remember only that the process required also copying some boot files from the "System" partition in the target (and ultimately: sole) Windows partition before having to restore also the botability of the converted disk using the bootsect command (with /rebuildbcd option, then /fixmbr, then /fixboot).

    the process took no more than 10 minutes, but unfortunately I don't find anymore the link I found with google despite hours of searches with all possible keywords.
      My Computer

  4.    #4

    What we have here that I have seen is Convert GPT Disk to MBR Disk - Windows 7 Help Forums.

    As it says in the tutorial this is a destructive process. I know of no other way to convert which could preserve your installation.

    However a search just now finds that the newly-popular Aoemi Partition Assistant can apparently do the conversion non-destructively. But I would be sure to back up data and a System Image just in case. Convert GPT to MBR or convert MBR to GPT without keep original dataConvert GPT to MBR or Convert MBR to GPT Disk without Losing Data
      My Computer


  5. Posts : 16,132
    7 X64
       #5

    That should do it.

    You may need to create winpe boot media. The program itself will do that for you.
      My Computers

  6.    #6

    I would imagine Aoemi doesn't write the MBR after converting GPT>MBR?

    So one would need still to Mark Win7 Partition Active and then run Startup Repair - Run 3 Separate Times.

    This is only experimental at this point.
    Last edited by gregrocker; 10 Apr 2014 at 10:54.
      My Computer


 

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