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Is there a way to convert MBR to GPT without reinstalling OS? RRS feed

  • Question

  • Hi guys.

    Server (http://www.supermicro.com/products/system/1U/6017/SYS-6017R-NTF.cfm)

    Four 2TB's disks.

    RAID 10 created

    Installed 2012 r2, but unable to use disk space larger then 2 TB's.I am able to create new SIMPLE volume, but unable to create 2nd one (see the Picture bellow, it's grayed out). Probaly because disk is set up as MBR.

    QUESTIONS:

    1. Is there a way to convert disk from MBT to GPT without the need to install Operating system?

    2. I don't remember that durring the installation of Windows 2012 r2 there was any option that you could choose that disk is MBR or GPT, is it?

    3. You probably need to run diskpart manually after you create RAID10 and create disk from MBR to GPT, right? And after that you go installing 2012r2 OS? Do you need to do any tweaks in BIOS settings?

    With best regards


    bostjanc


    • Edited by B_C_R Wednesday, February 17, 2016 9:48 AM
    Wednesday, February 17, 2016 9:46 AM

Answers

  • Hi guys.

    Server (http://www.supermicro.com/products/system/1U/6017/SYS-6017R-NTF.cfm)

    Four 2TB's disks.

    1. Is there a way to convert disk from MBT to GPT without the need to install Operating system?

    2. I don't remember that durring the installation of Windows 2012 r2 there was any option that you could choose that disk is MBR or GPT, is it?


    1. There are 3rd party partition tools (Google it) to do this but there is always an inherent risk so make sure you are backed up fully.

    2. Usually you select this in the BIOS or UEFI, where you have the option of MBR or GPT.  Usually, MBR and BIOS (MBR + BIOS), and GPT and UEFI (GPT + UEFI) go  hand in hand. This is compulsory for some systems (Windows), while optional for others (eg Linux).

    If you have not put a lot of work into the server yet, I would reinstall using UEFI+GPT.


    Miguel Fra | Falcon IT Services
    http://www.falconitservices.com



    • Edited by Miguel Fra Thursday, February 18, 2016 5:31 AM
    • Proposed as answer by Mary Dong Friday, March 4, 2016 6:29 AM
    • Marked as answer by Mary Dong Monday, March 7, 2016 1:21 AM
    Thursday, February 18, 2016 5:24 AM

  • Probably we would need to DOWNLOAD RAID drivers and put them on the USB keys and then running the command in command prompt (drvload D:\path_to_the_driver_inf_file.inf) before we run diskpart, right?


    bostjanc

    When you get to the diskpart screen look for a drivers selection, you should be able to just browse to where the inf driver file is located. No need to run commands.

    Miguel Fra | Falcon IT Services
    http://www.falconitservices.com


    • Edited by Miguel Fra Saturday, February 20, 2016 5:00 AM
    • Proposed as answer by Mary Dong Friday, March 4, 2016 6:29 AM
    • Marked as answer by Mary Dong Monday, March 7, 2016 1:21 AM
    Saturday, February 20, 2016 4:58 AM

All replies

  • Hi bostjanc,

    Thanks for your post.

    By default, if MBR disk has disk partitions, the convert to GPT is gray. You can change a disk from MBR to GPT as long as the disk does not contain any partitions or volumes. You may refer to the following guide:

    Change a master boot record disk into a GUID partition table disk

    If you have partitions on the disk, you may try to back up the whole disk, delete all partitions and then use the above method to convert the disk from MBR to GPT or you might need to use a third party utility.

    And for install server with GPT partition,  you could refer to the thread discussed before.

    https://social.technet.microsoft.com/Forums/sharepoint/en-US/2d897851-9aec-4377-b798-86a38a3e72f1/how-to-install-windows-server-2012-with-gpt-partition-on-a-clean-hard-drive?forum=winserver8setup

    Best Regards,

    Mary Dong


    Please remember to mark the replies as answers if they help and unmark them if they provide no help. If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com.

    Thursday, February 18, 2016 5:03 AM
  • Hi guys.

    Server (http://www.supermicro.com/products/system/1U/6017/SYS-6017R-NTF.cfm)

    Four 2TB's disks.

    1. Is there a way to convert disk from MBT to GPT without the need to install Operating system?

    2. I don't remember that durring the installation of Windows 2012 r2 there was any option that you could choose that disk is MBR or GPT, is it?


    1. There are 3rd party partition tools (Google it) to do this but there is always an inherent risk so make sure you are backed up fully.

    2. Usually you select this in the BIOS or UEFI, where you have the option of MBR or GPT.  Usually, MBR and BIOS (MBR + BIOS), and GPT and UEFI (GPT + UEFI) go  hand in hand. This is compulsory for some systems (Windows), while optional for others (eg Linux).

    If you have not put a lot of work into the server yet, I would reinstall using UEFI+GPT.


    Miguel Fra | Falcon IT Services
    http://www.falconitservices.com



    • Edited by Miguel Fra Thursday, February 18, 2016 5:31 AM
    • Proposed as answer by Mary Dong Friday, March 4, 2016 6:29 AM
    • Marked as answer by Mary Dong Monday, March 7, 2016 1:21 AM
    Thursday, February 18, 2016 5:24 AM
  • We ended with putting 2 disks in RAID1 two times.
    We had DISK 1,2,3,4 in RAID 10 before, now we have DISK 1,2 in RAID1 and DISK 3,4 in RAID1.
    Not Quite a desired situation but at least we got the hole 4 TB's available.

    We got stucked at diskpart.
    We put a 2012 R2 bootable USB key (created with http://wudt.codeplex.com/) and boot from it.

    At the language screen we hold down SHIT + F10, ran command prompt and diskpart, but the we weren't able to see any other disks except the bootable USB drive.

    Probably we would need to DOWNLOAD RAID drivers and put them on the USB keys and then running the command in command prompt (drvload D:\path_to_the_driver_inf_file.inf) before we run diskpart, right?


    bostjanc

    Thursday, February 18, 2016 6:43 AM

  • Probably we would need to DOWNLOAD RAID drivers and put them on the USB keys and then running the command in command prompt (drvload D:\path_to_the_driver_inf_file.inf) before we run diskpart, right?


    bostjanc

    When you get to the diskpart screen look for a drivers selection, you should be able to just browse to where the inf driver file is located. No need to run commands.

    Miguel Fra | Falcon IT Services
    http://www.falconitservices.com


    • Edited by Miguel Fra Saturday, February 20, 2016 5:00 AM
    • Proposed as answer by Mary Dong Friday, March 4, 2016 6:29 AM
    • Marked as answer by Mary Dong Monday, March 7, 2016 1:21 AM
    Saturday, February 20, 2016 4:58 AM
  • there is a way to convert MBR to GPT without reinstalling OS if your system and hardware support UEFI.

    If you want to convert MBR to GPT without affecting the OS, you need to use third party software, 

    such as AOMEI Partition Assistant. after the conversion, you have to enable UEFI boot mode before booting your computer, otherwise, you computer will fail to boot.

    there also is a way to use the space beyond 2TB without converting MBR to GPT. You can use Seagate Disc Wizard to mount the unallocated space as a virtual drive, so you can read or write with it.

    • Proposed as answer by PCHelpForce Friday, June 21, 2019 2:20 AM
    • Unproposed as answer by PCHelpForce Friday, June 21, 2019 2:20 AM
    • Proposed as answer by PCHelpForce Friday, June 21, 2019 2:20 AM
    • Unproposed as answer by PCHelpForce Friday, June 21, 2019 2:20 AM
    Monday, February 22, 2016 8:01 AM
  • https://docs.microsoft.com/en-us/windows-hardware/manufacture/desktop/windows-setup-installing-using-the-mbr-or-gpt-partition-style

    If you just installed it rather than messing with a bunch of problems later I would recommend these instructions. Just go into BIOS....change your boot to UEFI Boot Method and then reboot the computer. (follow instructions in this link)

    Friday, June 21, 2019 2:22 AM