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Based on the experience documented in Migrate from MBR to UEFI with an encrypted system partition

I'm considering the opportunity to migrate Windows 7 from the plain ol' MBR to the new GPT/UEFI boot before upgrading to Windows 8. I'm linking my previous post because when migrating Linux I experienced a few issued and learnt a lesson about GPT: don't trust simplicity. I'm not working on the same computer as the other post!!

Anyway, to make it short, I know that in order to boot from UEFI I need an EFI boot partition on first instance, then I must make sure that Windows restores the boot structures correctly once they are missing. I don't have encrypted partitions or other fancy things on this computer, just to clarify.

I'm asking you for any direct experience in the conversion.

Flight plan:

  • Backup important data
  • Run the tool to convert MBR to GPT from the system
  • Shut down and physically disconnect unneeded hard disks (just in case..)
  • Reboot into DVD recovery mode
  • Let recovery fix the boot problem (perhaps auto creating the EFI boot partition)
  • If it doesn't work on auto repair mode use bootrec /rebuildBcd
  • If that doesn't work I'm screwed

Questions:

  1. Does this tutorial on MBR/GPT conversion work on a live Windows system? The last time I used it it ran on a non-system disk and I could successfully shut down the machine the clean way
  2. Does Windows recovery automatically create the EFI boot partition shrinking the system partition?
  3. In case I'm screwed (read above) can I create the EFI Boot partition with GParted or similar tool? How large should it be? Then, does Windows Restore do its job?
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1 Answer 1

Such a conversion is possible, but is also risky and a bit of a pain. Something like your outline might work, but it's been at least a year since I did anything along those lines, and I don't recall the details of what I did. This article describes the process; however, it's based on using DUET to create an EFI environment on a computer without EFI support in the firmware. Thus, you'll need to ignore all the references to DUET if you follow that procedure. (This actually simplifies the conversion.)

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