What is needed to switch from Bios/MBR to UEFI/GPT?

Does that always require a clean install?
If so, why? Are different drivers needed or are other parts of the OS different?

The new Paragon Hard Disk Manager 11 Pro claims as one of its features:
Conversion of basic MBR to basic GPT disks

I wonder whether it would allow for such a migration without reinstalling everything from scratch.

Any ideas?

 

There are ways to do a migration from MBR to GPT but the manual steps take a fair bit of work. It is often easier to do a clean install from media to get the configuration you want. I believe someone in this forum posted instructions on how they did a clean install so it might be worth your time to search for it.

 

if you find it can you post it here, i'm interested too

 

It seems that the tool I mentioned above and an open source tool (gptgen) can perform the conversion of a partition.

But I also saw a remark from the author of gptgen that more seems to be necessary to be able to boot from it:
(Note that this merely converts the existing partitions to GPT format, and does not create Microsoft's required partitions, e.g. EFI system partition, MS Reserved partition, etc. - you need to create those partitions yourself after the conversion if you need them.)

 

Use the search, Luke! Anyway, here are the threads:

This thread has the preferred method of doing a reinstall: http://forum.notebookreview.com/lenovo-ibm/572616-t420-msata-uefi-only-20-sec-boot.html

This can be done too but it's quite long: Change the booting style of Windows Vista or 7 x86_64 versions from BIOS-MBR mode to UEFI-GPT mode without formatting or reinstalling

Finally, you can always try paying for the Paragon software but I haven't personally tried it so I can't vouch for whether it works or not.

 

It isn't difficult, but your best bet is definitely a clean install. That's the route I went, and everything has gone well.

 

I heard it is impossible to install Windows 7 in UEFI-only mode from the USb stick and that a boot from external DVD drive is required. Is that true or is it somehow possible to clean-UEFI-install route from an USB stick?

 

You are right. Installing Windows with a USB drive won't work for the UEFI Only install. If you google "UEFI install with USB", you'll find a forum thread that describes a "theoretical" way to do it but it's not confirmed to work.

However, you don't need an external DVD drive. UEFI Only Windows install works with the Thinkpad built-in DVD-ROM. See http://forum.notebookreview.com/lenovo-ibm/572616-t420-msata-uefi-only-20-sec-boot.html

This should work with regular SSDs and HDDs.

 

Thanks for the link that describes how to migrate an existing installation!
It confirms that it takes more than just switching the boot partition from MBR to GPT.
I looked at the documentation of the Paragon software, and it just seems to convert the partition itself, without creating the additional needed partition(s).

Given that I'll hold off trying the conversion. I don't want to do a clean install, having just completed the setup of my new Thinkpad, and the conversion of an existing system seems too involved for me.

Maybe someone will come up with a tool that does it all...

 

Provided, of course, you have one of those. I believe maticomp is one of those eagerly awaiting the delivery of an X220.

 

It's certainly possible -- I've done it on my x120e following these instructions to prepare the USB flash drive: [How To] Installing Windows 7 x64 To Your CR-48 (UEFI)

 

It seems that the Lenovo preload for sandy bridge based machines allows for both MBR/Legacy and UEFI type installations from the recovery disks. See this document (type MIGR-77353 in search box at Lenovo.com): Lenovo Support - Windows 7 Clean Installation - ThinkPad T420, T420i, T420s, T420si, T520, T520i and W520

While the document describes a clean install of Win 7 on a machine with BIOS configured in legacy mode, the document intro states:

"This install process is based upon default BIOS configurations of the listed Thinkpad systems. This means the OS install will be in standard Thinkpad BIOS hereafter known as legacy BIOS. There will be a separate installation document written purely from a UEFI BIOS configuration. The Lenovo Windows 7 preload is configured for Legacy BIOS in first boot order and UEFI second."

So, it seems you might be able to restore the system from the recovery partition or by using recovery cds after changing relevant settings in the BIOS to UEFI mode.