3TB drive of GPT type only showing 2TB - Why?

[SlimTim]

I have a 3TB Seagate hard disk which I converted to GPT type using AOEMI Partition Master Standard so that I could partition it into 2 drives of 1TB and 2TB for a total of 3TB. I converted the MBR to GPT but when I check the drive, it is showing total capacity of 2TB with partitions of 1TB each. Why is this happening and how do I fix it to get the full 3TB capacity? Windows 7 Disk Manager also shows only 2TB.


Thanks

 

[Paul Black]

Hi SlimTim, welcome to Seven Forums,

Could you please post an image of the Disk Management.

I hope this helps!

 

[dsperber]

I have a 3TB Seagate hard disk which I converted to GPT type using AOEMI Partition Master Standard so that I could partition it into 2 drives of 1TB and 2TB for a total of 3TB. I converted the MBR to GPT but when I check the drive, it is showing total capacity of 2TB with partitions of 1TB each. Why is this happening and how do I fix it to get the full 3TB capacity? Windows 7 Disk Manager also shows only 2TB.

I suspect that AOEMI didn't do the job expected.

Give Minitool Partition Wizard Free a try now, assuming it's possible to correct whatever AOEMI did.

 

[lehnerus2000]

SATA Controller Driver

I have a 3TB Seagate hard disk which I converted to GPT type using AOEMI Partition Master Standard so that I could partition it into 2 drives of 1TB and 2TB for a total of 3TB. I converted the MBR to GPT but when I check the drive, it is showing total capacity of 2TB with partitions of 1TB each. Why is this happening and how do I fix it to get the full 3TB capacity? Windows 7 Disk Manager also shows only 2TB.

This sounds similar to an issue I had when I first tried to use a 3TB HDD.
It was caused by a SATA Controller driver problem.

Check out this thread (Post #4 has the solution that worked for me):
3TB HDD GPT Problems

 

[jumanji]

Hi SlimTim,

You said "I converted the MBR to GPT". That makes me believe that your 3TB Seagate drive is a pre-windows 7 external HDD that rolled out of the factory as an MBR initialised and formatted external drive.

If that is true ( conditional statement ), the enclosure electronics + the HDD combination was designed to be so to make those drives compatible with Windows XP. Take the HDD out of the enclosure and plug it in as an internal drive if you want to initialise,format and use it as a GPT drive. Inside the original enclosure, you have to initialise and format it as an MBR drive to get the full 3TB. ( or Reconvert it from GPT to MBR to see full 3TB and partition it)

More insight here

4TB external disk is shown as MBR formatted. How is this possible? Solved - Windows 10 Forums

Hard Drive seems corrupt. 1 Partition now showing as 3 Partitions? Solved - Windows 10 Forums

 

[SlimTim]

Thanks for all of the suggestions. I deleted the partitions, and re partitioned it again with AOMEI Partition Master, rebooted my computer and now I can see the full capacity. Not sure why it didn't do it properly the first time. Never had that happen before which is why it had me puzzled.


Thanks again for all of the suggestions.

 

[dsperber]

Thanks for all of the suggestions. I deleted the partitions, and re partitioned it again with AOMEI Partition Master, rebooted my computer and now I can see the full capacity. Not sure why it didn't do it properly the first time. Never had that happen before which is why it had me puzzled.

Well, there IS a significant difference between (a) "convert MBR to GPT", and (b) delete all partitions and start over, creating new partitions from scratch using GPT.

Perhaps AOMEI has a problem with (a). Or, more likely, maybe there was something non-standard about how this drive looked in the first place when it was MBR since it simply is not possible to utilize a drive >2TB partitioned as MBR. So who knows what the condition of the MBR partition table on the drive is if you were initially trying to use a 3TB drive via MBR, since that's not actually supported? Who knows what AOMEI will do with a non-standard MBR situation?

But, if you wipe everything away as you just did in order to start over from scratch, and AOMEI now sees simply a blank 3TB drive, it can clearly have zero problem creating one or more partitions through GPT... from scratch, creating a genuinely proper GPT partition table.

Problem free via this "delete/create from scratch" method is totally understandable. "Conversion" from MBR to GPT on a drive >2TB which is an invalid situation, well who knows?

Anyway, you're in business now... thankfully since you didn't have any lost data (on the now deleted previous partitions on this drive) to worry about, or else you could restore it from a backup once you partitioned successfully using GPT.

Case closed.

 

[SlimTim]

Yes dsperber, you are probably correct. I did originally do a convert from MBR to GPT. But, as you mentioned, deleting all partitions and then prtitioning in GPT mode was the answer.