Windows 10: Convert 1.5TB disk from MBR to GPT

Recognising drives over 2.2TB as mbr requires special drivers on host pc. Problem is if you move drive to another PC, it will not be fully accessible unless drivers can be installed on new pc.

Actually, I do not really agree with statement "no harm", as any conversion exercise can crap out if unlucky. The risk is low but not zero - always assume the worst and backup critical data.

 

You are probably mistaken. I am not asking anyone to convert their over 2TB drives to MBR. I have merely stated over 2TB MBR drives were available for as long as Windows XP existed. As far as consumer HDDs are concerned these were available as external drives compatible with Windows XP. These over 2TB MBR drives are still existing and being used with Windows 7, Windows 8 and Windows 10. These drives use a special drive Translation circuitry built into the drive's SATA to USB bridge circuit inside the enclosure and as such need no drivers to be installed into OS. These external drives can be freely moved into any version of Windows.

As far as this thread is concerned the OP wants to convert his MBR drive into GPT. It is well known and proven that this GPT to MBR and viceversa can be done without data loss by third party software like Partition Wizard, AOMEI Partition Assistant and the like. And again if you read Brink's tutorial he has clearly mentioned " To be extra safe, it is always recommended to backup anything you do not want to lose first" and Ztruker is no novice *Smile. You already know that the conversion was successful. That he attempted it on a wrong disk was an accident which again he recovered.

 

I do have a critique though, which I will pass on to Aoemi. Why did they allow me to try to convert to GPT when the disk was already GPT? That should have raised an error and nothing should have happened. Especially since doing so obviously trashed the disk.

 

Yep, that is what one would expect. When time permits I shall do what you have done on my trial HDD and check what changes it made out of that GPT to GPT conversion *Smile.

 

Hi there
remember also some computers will ONLY boot from UEFI mode Bios -- so if say your OS is on a 256GB SSD there's absolutely no problem in having this as a GPT drive.

I'm really surprised why the standard command convert GPT didn't work from the command mode - that will convert a Disk to GPT in seconds without losing data (you can't do it the other way around though like that - to convert back to MBR you will lose data unless you save it first).

Cheers
jimbo

 

Glad you got it sorted mate.

If it makes you feel better there is a good reason to use GPT rather than MBR for data drives. The partition table in MBR drives is stored once only. On GPT it is stored twice (with checksums) - once at the start and once at the end so if the first partition table gets corrupted you can recover it from its backup. There is some other discussion here by my favorite GPT guru...

Not that I'm recommending particularly - just thought some justification might make you happy *Smile

You can even use something like gdisk and have both mbr and gpt partition tables on the same disk (but most of the time that would be rather silly!).

 

^ You are right upto a point that the GPT data - the GPT header, and the GPT partition tables - are backed up at the end of the HDD. In case the primary GPT data at the initial sectors gets corrupted, the backup will be automatically read and the disk will continue to be accessible as if nothing has happened.. The user wouldn't even know that the partition data has corrupted and it is now being read from the backup.

 

Hi there @cereberus

I have to disagree with your suggestion that it's pointless to have GPT drives if they are less than 2.2 TB -- on a laptop or typical machine you could be correct but remember if using MBR you can only have up to 4 primary partitions on Windows plus you can get into horrible screw ups with the hideous concept known as Logical Partitions. GPT which is based on the cocept of GUUIDS can have as many partitions as you want or need.

(With current GUUIDS there are more combinations than there are estimated seconds left until the end of the Universe -- never mind the lifetime of the Sun - probably another 5 Billion years or so --humans will have long since departed planet earth before then -- natural Sun warming as the Hydrogen gets burned up will make the planet uninhabitable anyway after around another 500 million years or so !!!).

There's no problem in having as many drives as possible as GPT - the only proviso if you have early hardware or running things like XP / W7 x86 on REAL hardware you can't boot from a GPT drive. On VM's you can set the boot to UEFI enabled even if the real (physical) machine boots from an MBR drive.

Cheers
jimbo

 

Hi Ztruker,

I couldn't replicate what you did to convert to GPT when the disk was already GPT *Smile. Please see the screenshot below .

When I tried it on already GPT Disk 2, both in the left Panel as well as the rightclick Menu of Disk 2 in AOMEI Partition Assistant, what I see is only " Convert to MBR". There is no way I can do a GPT to GPT conversion.

 

I agree re. more than 4 primary partitions on but very few people would use more than four on a data drive.

 

I wonder what I actually did then? What you see is how I would expect it to work.

I did this while booted from Kyhi's Rescue PE Environment. I'll boot it again and take a quick look.

 

MBR2GPT utility is available only for Windows 10 1703 or later, and also, it is available for system disk only. It should convert MBR-formatted system disk to GPT if all condition meet.
Indeed, AOMEI Partition Assistant is a nice alternative to MBR2GPT in Windows 10 when the version or OS not applicable. To convert data disk between MBR and GPT without data loss, the Standard (free) edition is sufficient. Yet, for system disk, the Professional edition is required.