OS2 World Community Forum

OS/2, eCS & ArcaOS - Technical => Setup & Installation => Topic started by: Martin Iturbide on September 20, 2017, 03:06:06 pm

Title: Converting GPT to MBR
Post by: Martin Iturbide on September 20, 2017, 03:06:06 pm
Hi Sigurd.

Can you please repost the information about converting GPT (GUID Partition Table) to MBR (Master Boot Record) ?
That post got delete on the forum restore and making this was on my TODO to try installing ArcaOS in Dual boot without removing the Win10 partition.

Title: Re: Converting GPT to MBR
Post by: Eugene Gorbunoff on September 20, 2017, 04:16:54 pm

google -> converting gpt mbr site:os2world.com

Title: Re: Converting GPT to MBR
Post by: Martin Iturbide on September 20, 2017, 05:16:02 pm
Thanks. I'm copying it since I don't know when Google flush the cache.

While I have some modern Laptops I allways wanted to install OS/2 on it AND preserve the preinstalled Operating System/Software. I.e. on my Sony Vaio Pro 13 there is a an ADOBE Software that is preinstalled but no media is shipped with the Laptop and so it is only part of the recovery media and can only be reinstalled within the whole recovery process.

One has to create Recovery media, that

- does only work when in BIOS SecureBoot and UEFI is checked
- does allways destroys the HDD/SSD Layout and changes it to GPT

The solution in the past years for me was to use DFSEE to wipe the whole SSD and reorganize everything with MBR Layout. This way I was not able to use the preinstalled Software/media but has to use a "usual" Windows 8.1 DVD to install it. And all the preinstalled Software has gone.... And it is allways a Kind of PITA to collect all necessary Drivers and so on....

But - I just realized a new way, that took only 20 minutes to convert the preinstalled GPT System into a MBR Layout and preserving everything!!

It was so easy to use, even if it may Sound crytic, but I am not a Linux Expert nor Commandline Expert - and it there was no Need for this skills!

In short:

I allways looked for this kind of tool, all I was able to find in the past have been able to convert GPT in MBR - EXCEPT of the Operatingsystem Partition - what made it allways useless for me.

Yesterday evening, where i decided to give OS/2 a comeback on that Sony Vaio Pro 13 I found by accident this page:


It is in German but you can use onlinetranslator to read it.

In short I did:

I restored Windows 8.1 using the Recovery Media Set I created years ago, so it was with UEFI, Secure Boot and GPT

Then to convert I:

- download the Linux System GMRL that is mentioned there http://grml.org/download/
- burned a CD from it (using USB DVD Writer)
- restarted my Sony Vaio, went to BIOS, changed
  - UEFI to Legacy
  - disabled SecureBoot
- booted the CD
- followed the instructions that are mentioned on the page of evilazarel
- restarted
- Windows 8.1 did start but showed Problems (as mentioned on the page already)
- so I inserted a "normal" Windows 8.1 DVD, booted from it and let it repair the Windows installation (2 Minutes work)
- I restarted and there it was, without GPT, without UEFI, without Secureboot it worked just like before, no difference!

I then changed the bootloader of Windows 8.1 to the Windows Drive C: as I described some years ago here: http://ru.ecomstation.ru/showarticle.php?id=214

And then I downloaded this tool https://www.heise.de/download/product/minitool-partition-wizard-78907 to shrink the Windows 8.1 Partition, and move it a bit to gain 16GB free for my OS/2 clone in front of the Windows Partition.

The only Thing to do now is to install ArcaOS 5.01 (if you like) - or in my case to install Airbootmanager and then restoring my OS/2 clone using DFSEE.

So I do have OS/2 alongside the once Preinstalled Windows 8.1 with all ist customized Drivers and Software  :D

And it may be interesting for ArcaNoae or whoever that there is a Chance to convert GPT to MBR INCLUDING the System Partition. One may have a deeper look in the way how GRML works, if interested in.

So, I hope these informations can help and wish you all the best!