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Mixing GPT and MBR hard drives in the same computer

RVT02 Posted messages 43 Registration date   Status Member Last intervention   -  
RVT02 Posted messages 43 Registration date   Status Member Last intervention   -

Hello,
in view of eventually converting all my hard drives to GPT, I would like to know if it is possible to have, at the same time on the same computer, an MBR hard drive containing the Windows 10 operating system and one or more GPT hard drives (converted to GPT or formatted to GPT if conversion is not possible).

The MBR to GPT conversion seems possible without data loss, but initially I would like to keep the hard drive with Windows in MBR, then gradually convert the other hard drives in the computer from MBR to GPT (by converting if there is no risk of data loss, or otherwise by backing up and then formatting to GPT and restoring from the backup).

There may be more risk in converting an MBR hard drive containing the Windows operating system to GPT, which is why I would prefer to first gradually convert all my other data drives from MBR to GPT, and then ultimately convert the hard drive containing Windows from MBR to GPT (or consider reinstalling Windows in GPT if conversion is not possible or not recommended).

Thank you in advance for your opinions or experiences.

4 answers

  1.
    thev Posted messages 2008 Registration date   Status Member Last intervention   722
     

    Hello,

    I don't really see the point for an individual to convert MBR disks that are not linked to an operating system into GPT. As for me, all my data disks are in MBR.

    The GPT disk is necessary to boot an operating system from a UEFI BIOS. If the PC's UEFI BIOS does not have the CSM option, then the GPT disk is mandatory.

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  2. flo88 Posted messages 28493 Registration date   Status Contributor Last intervention   Ambassadeur 5 170
     

    Hello

    Additionally, only W11 officially requires its installation disk to be in GPT and the BIOS in UEFI.

    However, other disks within the PC can be in MBR without any issues. They will be perfectly recognized by Windows.

    Example where we see an MBR disk coexisting with GPT under W11:

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  3. RVT02 Posted messages 43 Registration date   Status Member Last intervention   2
     

    Hello flo88,

    so there’s no issue having Windows 11 (or 10) in GPT and other hard drives in MBR.

    But in my case, it's to keep Windows 10 in MBR for now, but on the other hand, start transitioning my other disks from MBR to GPT with a view to eventually getting everything to work in GPT when I switch to Windows 11.

    The BIOS of my motherboard offers the mixed UEFI and Legacy boot option, so I should be able to continue using the hard drive containing Windows 10 in MBR and convert my other hard drives from MBR to GPT.

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  4. RVT02 Posted messages 43 Registration date   Status Member Last intervention   2
     

    Hello thev,
    So there is no need to convert to GPT for disks that do not contain the Windows operating system, even if the hard drive that contains Windows is in GPT.

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    1. brucine Posted messages 24948 Registration date   Status Member Last intervention   4 179
       

      Hello,

      In case any of these data disks exceeds 2 TB, Windows may have difficulty addressing it in MBR.

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      1. RVT02 Posted messages 43 Registration date   Status Member Last intervention   2 > brucine Posted messages 24948 Registration date   Status Member Last intervention  
         

        Hello Brucine,
        yes indeed in the case where the hard drive is over 2TB

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