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Windows 2012 R2 Hyper-V Migrate Gen1 to Gen2

If you need migrate your existing Gen1 VM to Gen2 VM, there is simple solution. You don't need double take move (or any other 3rd party sw). Just trun of your VM (make backup!!) and start conversion.

  1. Backup
  2. Note IP config and license key. New VM will have new NICs and new hardware IDs. Maybe you can edit VM .xml configs and copy & paste HW IDs, but I haven't tried it yet and not sure if it will work (but I think it should).
  3. Turn off BitLocker and decrypt your drives (if you are using)
  4. Turn off VM
  5. Mount VHD in your Host OS
  6. Convert VHD from MBR to GPT with gptgen: http://sourceforge.net/projects/gptgen/
  7. Delete System Reserved partition
  8. Create UEFI partitions
    • create partition EFI size=100 offset=1
    • format quick fs=fat32 label="System" 
    • assign letter=S (don't use ntfs, it won't work!)
    • create partition msr size=128 offset=103424
  9. Repair booting: bcdboot c:\windows /s s: /f UEFI
  10. Create new Gen2 VM and attach your edited VHD
  11. Boot Gen2 VM (you can also switch on secure boot)
  12. Reapair networking, reactivate OS
  13. Enjoy faster booting and online System VHD resizing.


Comments (4) -

Create UEFI partitions
What was the size of the partition?

format quick fs=fat32 label="System" assign letter=S
In Windows 2012 there is no option assign letter


size is 100 MB (size=100 means 100 MB, default unit is MB)

if you are not able to assign letter via diskpart (I'm sure, it is possible), try computer management mmc


How you created 2 partition on 100 MB if initial was 100 in size?

Correct your article correctly as follows:
format quick fs=fat32 label="System"
assign letter=S


sorry, I didn't understood ...
initial partition (mbr) was 350 MB


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