HDD Partition becomes unallocated after Windows 10 installation.

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  1. Posts : 2
    Windows 10 pro

    HDD Partition becomes unallocated after Windows 10 installation.

    I have a SSD where my operating system is installed.

    I also have a 3 3TB drives.

    A 746.52 partition on one of the drives became unallocated after installation of windows 10.

    I've managed to recover all the data from the unallocated partition. Would now like to fix the partition.

    I think it may be something to do with MBR/GPT?

    Here's a screen print from disk management.

    HDD Partition becomes unallocated after Windows 10 installation.-screen-print.png

    Any help appreciated.
      My Computer

  2. Posts : 2,487
    Windows 10 Home, 64-bit

    Can you boot with Disc 0 completely disconnected?

    I'd guess you can. If so, I don't think you need partition I on disc 0.

    You should be able to make disc 0 to behave like disc 2, which is also a 3 TB drive. Disc 0 appears to be initialized as MBR. If you want it do be like disc 2 with a single partition covering the entire 3 TB, you'd need to re-initialize it as GPT, just like disc 2. You'd have to move that data off of the J partition and then delete the J partition to do that. I think there are applications that say they can convert from MBR to GPT without losing data, but I wouldn't trust that. I'd plan to wipe that drive and start over--but you first need to confirm you can boot with disc 0 disconnected.

    Was that drive 0 connected when you installed to the SSD? If so, usually a bad idea to have more than 1 drive connected.
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  3. Posts : 2
    Windows 10 pro
    Thread Starter

    The fatal error was not disconnecting the other HDD, which I usually do. Just got sloppy!

    Thanks for the reply.

    I was hoping to find a way to get the unallocated partition working, bought a new 3tb drive today to clear J and start from scratch in case this was a non starter.

    Anyone have an idea what caused the problem?
      My Computer

  4. Posts : 2,487
    Windows 10 Home, 64-bit

    winstainforth said:
    I was hoping to find a way to get the unallocated partition working,
    You can't "get it working" as is. It's not a partition. It's unallocated space. MBR discs aren't going to recognize 3 TB on a disc--only a little over 2 TB.

    You can start over with that disc, initializing it as GPT. As I mentioned in my first post.
      My Computer

  5. Posts : 1
    Windows 10 Pro

    Were you able to fix it, and how did you recover the data? I am having the same issue and was not sure what to do. I would have sent you a PM but I have less than 5 posts.
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  6. Posts : 1
    Windows 10


    I just registered here to share this thread:


    MS hasn't been very helpful, but there is some advice there which may be of use in recovering your data.
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  7. Posts : 2
    Windows 10 Home (x64) Version 1511 (build 10586.104)

    try reinstalling the driver!

    I had the exact same problem. running a Seagate HDD with 6TB, 2TB C:/ and 4TB for storage

    I spent 2 weeks trying out various recovery programs, popping it into a toaster and seeing if I could pull the data off the unallocated storage onto an external, and even booting into a live USB of Lubuntu but nothing was working.

    Then I tried running the seagate tool that came with it and it gave me a flag saying that it needed the Virutal Disk Driver to be installed

    I installed the driver, gave the partition a letter and presto, all files and the partition were back good as new!

    yup, all that effort for 2 weeks when all that happened was that the upgrade from 7 to 10 deleted a driver.

    Here's to hoping my experience will help others especially since this board was a top result when search for answers!
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  8. Posts : 1
    Windows 10 Pro Insiders Preview 14267

    My machine boots to Windows 10 insiders preview, or Windows 8.1. Windows installations are on separate hard drives. Upon the previous major update to build Windows 10 insiders preview, build 14257, my secondary hard drive popped up as unallocated in Windows 10. Not only that, it couldn't be accessed by diskpart, or other various and sundry partition software out there. It's a 1 TB WD Black hard drive. It was working fine in Windows 10, before the update. In fact when I boot to Windows 8.1 it still works fine and all my data is intact. So. Check your drivers, before you go purchasing new hardware or losing critical data. In my case it was the sata driver for my asus motherboard. Once I installed that. The drive popped back into drive manager as active and healthy. I just had to give it a drive letter, and it was back to normal in Windows 10.
      My Computer

  9. Posts : 2
    Windows 10 Home (x64) Version 1511 (build 10586.104)

    michaelshepard2 said:
    I don't think it has something to do with MBR/GPT. it seems that files sytem of the partition gets damaged. To make the partition work again, you can simply format it since you have recovered all data from it.

    For me it was because the "virtual driver" for seagate was erased by the upgrade from win7 to win10. Because of that same issue it prevented me from recovering the files even through mini tool recovery and various other programs (even dual booting into linux did nothing). Yes I could see the files in the recovery tools but I couldn't extract them. Of course after I figured out what was going on I simply re-installed the virtual driver which recognized the 3TB partition and then I gave it a drive letter and everything was there, none the worse for wear.

    I won't deny, I was one step away from just reformatting it but luckily I didn't because I would've kissed a TB or so of files goodbye, plus knowing what I know now, it wouldn't have resolved the issue.
      My Computer

  10. Posts : 1

    Scanned drive with mini-tool for 24 hrs!! Unnecessarily!!

    I scanned my hard drive for 24 hrs with mini-tool! .. before I realized that I only needed to uninstall hard drive driver to let it re-install!! Uggggg!! All working well now :). (Almost reformatted also ... so. glad. I . didn't .) Thanks!!
      My Computer


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