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I formatted a 8TB Seagate IronWolf hard drive via an external USB enclosure. It worked fine: Windows 10 recognized both GPT partitions:

  • Partition 1: GPT, 128 MB
  • Partition 2: GPT, 7451 GB.

But when connect it direct via SATA, Windows recognize the drive as MBR:

  • Partition 1: MBR, 2048 GB, Protective Partition.
  • Unallocated: 5404 GB

When put the drive back into the USB case, all works fine. How can I force Windows to recognize the hard drive type as GPT?

Setting the partition type id with a tool like Partition Wizard, doesn't make sense, because the drive which holds the partiton, is recognized as MBR. Of course I dont't want to reformtat it, because it holds a prtition with data. Software like Active Partition Manager stops on a convert to GPT action with: "Unable to convert GUID Partition Table. Impossible to place partitions outside of target area on devices having GPT".

Hardware details:

  • Windows 10 x64
  • Seagate Archive HDD v2 8TB (ST8000AS0002-1NA17Z)
  • AMD Ryzen 7, Asus Prime X370-Pro

Correct recognized partiotioncs (via USB):

  • Partition 1: ID=E3C9E316-0B5C-4DB8-817D-F92DF00215AE (GPT, 128 MB)
  • Partition 2: ID=EBD0A0A2-B9E5-4433-87C0-68B6B72699C7 (GPT, 7451 MB, Encrypted via VeraCrypt)

Screenshot, Hard drive manager, GPT

Wrong recognized Partitions (via SATA):

  • Partition 1: GPT Protective Partition(GPT, 2048 GB)
  • Unallocated: 5404 GB

Screenshot, Hard drive manager, MBR

Any idea why its not possible to operate my drive internal?

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    Your likely running into a problem with the sector size difference between what the adapter said it was and what your hdds sector size actually is. You didn't indicate if your IronWolf was 512 or 4K provide specifics. Model number didn't result in accrurate search results so provide the product specification page – Ramhound May 6 '17 at 14:42
  • VeraCrypts GPT support is experimental, your problem, is a combination of sector sizes and VeraCrypt GPT support being experimental – Ramhound May 6 '17 at 14:46
  • I suggest you move the data off, format the hdd, and simply recreate the partitions. There is no safe way to correct the sector size at this point – Ramhound May 6 '17 at 14:51
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    @Tobsd - So yeah; Your external enclosure advertised the sectors were 512e instead of 4K. So your problem is a combination of, incorrect sectors size and likely how VeraCrypt actually deals with GPT (appears they put a MBR partition within a GPT partition) but that's a question for a VeraCrypt developer – Ramhound May 6 '17 at 15:56
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