I have received a new Lenovo T420 laptop with Windows 7.

The disk now contains:

  • a hidden SYSTEM_DRV boot partition (1.17 gb, 400mb used). I'm guessing this is the EFI partition, the laptop comes with UEFI instead of legacy BIOS. This partition is NTFS formatted.
  • the win7 partition
  • a rescue partition

As I've come to understand, the bios is EFI but MBR is used, not GPT.

Since I'm going to install linux anyway, I figured it would be a good idea to convert to GPT.

I found the tool fdrive, that offers the option to covert the MBR partition table to GPT partition table. But I don't know what happens with that boot partition, with the windows installation and things like that.

If anyone has looked into such issues please advise. Maybe there's something I dont understand.

  • Why do you care its its MBR or GPT? – soandos Jul 26 '11 at 4:56
  • @soandos Well, this is a powerusers board isn't it? For experimentation mostly. But I think I'll give up on this idea for the following months, as I just found there are a couple of very serious bugs in ubuntu that affect this exact thing I want to do. – nick_uk Jul 26 '11 at 11:30

I guess the original poster is not going to change his mind about the conversion after reading my post :-) But since the question is up-voted, here are some hints:

The first partition is more likely to be a Windows-specific "system" partition, particularly if it is NTFS-formatted (the EFI partition should be FAT-formatted to be useful to the largest number of systems.)

EFI systems using MBR-formatted disks often boots using "legacy mode" (Compatibility Support Module), so to all effects, they appear to the OS as BIOS systems, not as EFI ones. In the case of Windows, the boot process of the operating system itself, after the boot manager, is a bit different (winload.exe against winload.efi); so fiddling with it is a bit risky. In addition, you need to add a EFI system partition which is presently missing (although reconverting the SYSTEM_DRV can be used for that purpose, it is not straightforward.) Furthermore, the recovery system provided by the vendor will blindly assume the computer operated in BIOS mode, so running it even by accident is likely to make things worse, not better: so it should be removed, which means removing one more safety mechanism in case something unexpected happens.

Since BIOS is better understood than EFI, it is therefore recommended to either consider the system as a purely dispensable experimentation machine (and then it is easier to start from scratch); or to stay with the original MBR formatting and BIOS booting.

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