Convert 1.5TB disk from MBR to GPT

Ztruker · 01 Jan 2018

cerebus,I know there is no reason to do so. As I said in my original post: No special reason, just because. I just wanted all my drives to be GPT. Guess I was bored :) Also, I'm hardly a newby. I asked, Shawn answered. 2ndly, I had never tried a MBR to GPT conversion before and wanted to see how it worked. The answer is, if you are careful and select the right drive, it works very well.

Anyway, all is well now. EaseUs Partition Recover Wizard ran overnight and I just now had it do the actual recovery and it worked perfectly and all 4 partitions are back and usable again.

This is what it looks like now and how it looked before.

Convert 1.5TB disk from MBR to GPT-image.png

... and all 3 disks are now GPT as I wanted:

Code:

DISKPART> list disk

  Disk ###  Status         Size     Free     Dyn  Gpt
  --------  -------------  -------  -------  ---  ---
  Disk 0    Online          232 GB      0 B        *
  Disk 1    Online         1863 GB   130 MB        *
  Disk 2    Online         1397 GB  2048 KB        *
  Disk 3    No Media           0 B      0 B

so the new year is off to a good start, and I learned something.

Brink · 01 Jan 2018

Great news Rich.

jumanji · 01 Jan 2018

Ztruker said:

.....,I know there is no reason to do so. As I said in my original post: No special reason, just because. I just wanted all my drives to be GPT. Guess I was bored :) Also, I'm hardly a newby...... I asked, Shawn answered....

Yep, that is it

. As long as it is not technically forbidden, there is absolutely no harm in converting an MBR to GPT and GPT is not limited to disks over 2.2TB just like MBR is not necessarily limited to 2.2TB. ( Using advanced formatting, upto 16TB disks can be MBR disks. We had those till Windows XP - which does not recognise GPT - lost support. )

cereberus · 01 Jan 2018

jumanji said:

Yep, that is it

. As long as it is not technically forbidden, there is absolutely no harm in converting an MBR to GPT and GPT is not limited to disks over 2.2TB just like MBR is not necessarily limited to 2.2TB. ( Using advanced formatting, upto 16TB disks can be MBR disks. We had those till Windows XP - which does not recognise GPT - lost support. )

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.

jumanji · 01 Jan 2018

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 :). You already know that the conversion was successful. That he attempted it on a wrong disk was an accident which again he recovered.

Ztruker · 02 Jan 2018

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.

jumanji · 02 Jan 2018

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 :).

jimbo45 · 03 Jan 2018

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

lx07 · 03 Jan 2018

Ztruker said:

I know there is no reason to do so. As I said in my original post: No special reason, just because. I just wanted all my drives to be GPT. Guess I was bored :) .

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 :)

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!).

jumanji · 03 Jan 2018

^ 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.