Convert 1.5TB disk from MBR to GPT

I want to convert a 1.5TB MBR disk to a GPT disk. My other two disks are GPT so I'd like them all to be. No special reason, just because.
When I tried mbr2gpt /validate /disk:2 I get

ERROR: MBR2GPT can only be used from the Windows Preinstallation Environment. Use /allowFullOS to override.

I can run this from WinPE but will it do what I want? My system is already a UEFI/GPY system, I just want to convert Disk 2 from MBR to GPT.

Code:

DISKPART> list disk

  Disk ###  Status         Size     Free     Dyn  Gpt
  --------  -------------  -------  -------  ---  ---
  Disk 0    Online          232 GB      0 B        *
  Disk 1    Online         1863 GB   130 MB        *
  Disk 2    Online         1397 GB  1024 KB
  Disk 3    Online           14 GB      0 B        *
  Disk 4    No Media           0 B      0 B

Code:

Disk 0
Volume ###  Ltr  Label        Fs     Type        Size     Status     Info
  ----------  ---  -----------  -----  ----------  -------  ---------  --------
  Volume 1     C                NTFS   Partition    232 GB  Healthy    Boot
  Volume 2         Recovery     NTFS   Partition    499 MB  Healthy    Hidden
  Volume 3                      FAT32  Partition    100 MB  Healthy    System
Disk 1
Volume ###  Ltr  Label        Fs     Type        Size     Status     Info
  ----------  ---  -----------  -----  ----------  -------  ---------  --------
  Volume 4     D   Lenovo_D     NTFS   Partition    732 GB  Healthy
  Volume 5     E   Lenovo_E     NTFS   Partition    732 GB  Healthy
  Volume 6     F   Lenovo_F     NTFS   Partition    378 GB  Healthy
  Volume 7     V   KYHI         FAT32  Partition     19 GB  Healthy
Disk 2
Volume ###  Ltr  Label        Fs     Type        Size     Status     Info
  ----------  ---  -----------  -----  ----------  -------  ---------  --------
  Volume 8     G   Lenovo_G     NTFS   Partition    698 GB  Healthy
  Volume 9     H   Lenovo_H     NTFS   Partition    698 GB  Healthy

Hello Rich, :)

Since this is a data disk and not the OS disk, you could use an option in the tutorial below to convert the MBR disk to GPT without data loss.

Convert MBR Disk to GPT Disk in Windows 10 Hardware Drivers Tutorials

Thanks Shawn. I just tried it and it said it worked but when I booted back to Win 10 the drive no shows as unallocated. All data is lost.

Code:

DISKPART> list disk

  Disk ###  Status         Size     Free     Dyn  Gpt
  --------  -------------  -------  -------  ---  ---
  Disk 0    Online          232 GB      0 B        *
  Disk 1    Online         1863 GB  1863 GB        *
  Disk 2    Online         1397 GB  2048 KB        *
  Disk 3    No Media           0 B      0 B

Code:

DISKPART> sel disk 1

Disk 1 is now the selected disk.

DISKPART> detail disk

ST2000NM0011
Disk ID: {10800FF6-5858-9090-8081-828310111213}
Type   : SATA
Status : Online
Path   : 1
Target : 0
LUN ID : 0
Location Path : PCIROOT(0)#PCI(1F02)#ATA(C01T00L00)
Current Read-only State : No
Read-only  : No
Boot Disk  : No
Pagefile Disk  : No
Hibernation File Disk  : No
Crashdump Disk  : No
Clustered Disk  : No

There are no volumes.

Code:

DISKPART> sel disk 2

Disk 2 is now the selected disk.

DISKPART> detail disk

ST31500341AS
Disk ID: {10821BFB-5858-9090-8081-828310111213}
Type   : SATA
Status : Online
Path   : 2
Target : 0
LUN ID : 0
Location Path : PCIROOT(0)#PCI(1F02)#ATA(C02T00L00)
Current Read-only State : No
Read-only  : No
Boot Disk  : No
Pagefile Disk  : No
Hibernation File Disk  : No
Crashdump Disk  : No
Clustered Disk  : No

  Volume ###  Ltr  Label        Fs     Type        Size     Status     Info
  ----------  ---  -----------  -----  ----------  -------  ---------  --------
  Volume 4     D   Lenovo_G     NTFS   Partition    698 GB  Healthy
  Volume 5     E   Lenovo_H     NTFS   Partition    698 GB  Healthy

The drive I converted from MBR to GPT is fine, has Lenovo_G and Lenovo_H on it. I lost me D: and E: partitions on drive 3. D: I have backeup up from Friday so no big deal and E: is nothing I care a whole lot about, but I wonder what happened.

Is there any way to recover this? Probably not.

Which option did you use?

I used Aomei Partition Master from Kyhi's Rescue WinPE ISO. I right clicked on the disk and selected convert to GPT.

I think this may be a self inflicted wound. The first time I tried it it failed when I clicked on Apply, though I don't remember the error message but I suspect I was on the wrong disk, the one that is now showing No volumes. It used to have D: E: F: and V: (where Kyhi's WinPE was installed).

I'm running the complete scan of EaseUS Partition Recovery Wizard now. Taking a long time but so far has found D: which is the one I need the most. I'll let it run over night.

jumanji, I don't want to run any other Disk Management stuff until EaseUS finishes. If it doesn't resolve the problem I post the info you requested.

I'm going to bed.

Happy New Year to all.

For clarity, there is ABSOLUTELY no point in converting a DATA only drive from mbr to gpt if the drive is less than 2.2TB.

You only need gpt if over 2.2 TB or if drive contains the Operating System and converting to UEFI.

I am afraid guys, the OP should really have been told this rather than methods how to convert drive, and then OP would not have got in a mess.

AddRAM said:

I didn't see the point in doing it either.

I always keep my install drive MBR and my storage drives GPT.

I do exact opposite - install as gpt for UEFI, and drives as mbr unless over 2.2TB.

I just like having 1 entire partition for Windows, it's so much easier to image that way.