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ubuntu@ubuntu:~$ sudo fdisk -lu

WARNING: GPT (GUID Partition Table) detected on '/dev/sda'! The util fdisk doesn't support GPT. Use GNU Parted.

Disk /dev/sda: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0xd033d792

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048      206847      102400    7  HPFS/NTFS/exFAT
/dev/sda2          206848   986601471   493197312    7  HPFS/NTFS/exFAT
/dev/sda3       986601472  1953519615   483459072    7  HPFS/NTFS/exFAT


/dev/sda contains GPT signatures, indicating that it has a GPT table.  
However, it does not have a valid fake msdos partition table, as it should.  
Perhaps it was corrupted -- possibly by a program that doesn't understand GPT partition tables.  
Or perhaps you deleted the GPT table, and are now using an msdos partition table.  
Is this a GPT partition table?

So when I try to install ubuntu I get a whole TB of unallocated disk. However I can see the 2 partitions mounted on ubuntu when I run "try ubuntu" I've created the ntfs partition on /dev/sda3 in an effort to fix the GUID table without success.

Is there any way to fix this so I can install ubuntu on /dev/sda3?

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Still affected by this issue? – Braiam Feb 7 '14 at 2:16
up vote 1 down vote accepted

To fix your problem, follow these steps:

  1. Boot the emergency disk and open a text-mode shell.
  2. Type "gdisk /dev/sda" (change "/dev/sda" to whatever is appropriate to access your hard disk, if necessary). The program is likely to complain that it's found both MBR and GPT data, and will ask which to use. It doesn't matter which you tell it to use.
  3. At the "Command" prompt, type "x" to enter the experts' menu.
  4. At the "Expert command" prompt, type "z" to "zap" (destroy) the GPT data.
  5. Type "y" in response to the confirmation about destroying the GPT.
  6. Type "n" in response to the query about blanking the MBR. Caution: If you answer "y" here, you'll destroy your Windows partition(s)!
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