HDD is both GPT and MBR and cant convert MBR

[Carl Blance]

Hi there,

So currently I'm building a lab PC and it had a HDD in it previously. So I stuck it in my main rig and found it was using MBR. So I left and installed a OS on to it, and created smaller partitions (3TB Drives).

So when I do the switch over it wont run, so figured it was the MBR which it was. However my issue is now that I've deleted the partitions that had my original OS on it. It's remained as an unallocated MBR partition, where the other 2TB is GPT.

So my question is how can I convert this fully to GPT

I've tried reformatting the drive with Control Panel > Disk Management. MBR Partition is grayed out, but the remaining 1TB that's allocated can be modified.

Tried using diskpart and following these steps in this .jpg image
http://www.disk-partition.com/diskpart/images/diskpart-initialize-disk-4125/diskpart-initialize-disks.jpg

But get error "Disk part failed to clear disk attributes"

So my second question is would have my main PC, created some Read Write Security access to that MBR partition, and hence why I can't modify it.

 

[RealBeast]

Try diskpart again, but this time use:
diskpart
list disk
select disk n (where n is the 3TB target disk)
clean
exit

Then you can initialize it as GPT in disk management and format it without partitions.

 

[Carl Blance]

Try diskpart again, but this time use:
diskpart
list disk
select disk n (where n is the 3TB target disk)
clean
exit

Then you can initialize it as GPT in disk management and format it without partitions.

Tried it and this is the odd bit, it says it's one unallocated object in CMD, but if you look in Disk Management you will see two objects, one which you can modify, and the other (the 700GB MBR) cannot be touched. I'll try a few things in a couple of hours. It's a really odd issue.

 

[D_Know_WD]

Hi there Carl Blance,

You can see if writing zeros on the HDD with a third party tool would help: http://www.tomshardware.co.uk/answers/id-1711997/software-wipe-hdds.html

Make sure you don't have any data stored on there.

Cheers,
D_Know_WD

 

[RealBeast]

Yes, I agree that I would either use a clean all command in diskpart instead of clean, or better yet use the free version of DBAN on the drive. Either will write a zero to every sector on the drive and hopefully give you a single large unallocated partition.

Make sure that you are doing this on a computer capable of mounting a 3TB drive (i.e. both the hardware and software so no Windows XP or earlier).