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I recently acquired a new HD (with 3TB) to upgrade from my current 500GB HD. I cloned onto the new HD using CloneZilla and now I'm trying to repartition the new HD, but every tool tells me when I try to resize the NTFS partition that holds my Win7 that there's no available space even though it also shows a 2.5TB unallocated block of memory. Any ideas on what's happening? Thanks in advance for any help.

The tools that I've tried are EaseUS and Partition Wizard and the Win7 Partition Tool.

EDIT: So I did some research on this whole GPT vs MBR thing and it seems to me that I should be able to at least expand my Win7 partition to the 2TB limit

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Did you convert the new drive to GPT? Or was the old drive already GTP? Because if you cloned an MBR formatted drive then the max usable size is 2TB. – Hennes Jan 20 at 21:08
I'm not particularly knowledgable about those properties, could you elaborate on them and/or tell me how to find out? – avorum Jan 20 at 21:10
There are two (major, PC) types of partition table. MBR, which has been around for a long time and can only deal with disks of 2TB or less, and GPT, which is much newer but can handle much, much larger disks (and doesn't need any of that "extended partition" silliness to have more than four partitions). – Darael Jan 20 at 21:15
@avorum You can also read more about GPT vs MBR on Wikipedia – Luke Jan 20 at 21:21
Do you know how to determine which they are? – avorum Jan 20 at 21:21
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2 Answers

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You will not be able to convert to GPT for a disk you are booted from. In order to boot in legacy bios mode you will need a 2mb partition at the start of a GPT disk formatted as a BIOS partition for the boot loader to be installed to for linux, however for windows it is not supported at all. (This was included in MBR by default, but is not in GPT because you can make an EFI partition to support EFI boot instead). I'm not aware of a simple way to change a bootable device to/from GPT.

The other problem is that windows only supports booting from a GPT drive if you boot in EFI mode, so you will need to boot your windows install media in EFI mode so that it will support using GPT disks. Basically legacy booted windows setup supports MBR only for install and EFI boot windows setup supports GPT only.

tl;dr: reinstall is required.

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If that is so, would it be possible to allocate an empty partition and then transfer the Win7 filesystem over? I don't still have the install disk for my Win7 so I don't think I can just reinstall onto the new HD – avorum Jan 21 at 5:02
You will need one to use EFI mode, as the installer installs a different boot loader in to the EFI partition that will chain load Windows. You could create the new install and leave space for a partition, then copy the partition's contents over from your old drive to the new partition. If you have access to a windows disk you can create a bootable USB key; as for booting it in to EFI mode you would need to specify the EFI option; usually if you press the button to choose boot device on startup it will have something like 'UEFI: sandisk cruzer' and 'sandisk cruzer', just choose the uefi one. – Justin Jan 21 at 8:11
How do I set up a new partition to use EFI? – avorum Jan 21 at 16:08
All you have to do is boot the windows setup in EFI mode, and then it will install the EFI boot loader and use GPT for the partition table; It doesn't support anything else in the windows setup. So as I said, find your boot device selection menu (F8 on Asus motherboards, F12 on IBM servers, etc at the BIOS/EFI screen) and then choose the one that shows EFI:[device]. If you want to use a USB key it only needs to be in FAT32 or UDF mode, and then just copy the files on the windows CD over; it doesn't need any boot loader as such to be manually installed for EFI, just the EFI folder. – Justin Jan 22 at 0:00
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A probably reason is that the oldl disk was formatted using the MBR scheme. That one only supports for drives up to 2TB.

You can install of clone a MBR to a 3 TB drive, but then you are either limited to the first 2TB, or you get problems with software which wraps around. (It counts to 2TB, then starts again at zero).

If the drive has a MBR then you can convert it to GPT via drive management. (See picture below). However make a backup before you try that.

Image of windows disk management

[Edit], to start it, go to [start] and type compmgmt.msc, or go right click on the [My computer] icon on the desktop.

enter image description here

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Where can I find the Computer Management program that you're using in the screenshot in Win7? – avorum Jan 20 at 22:06
If the Convert to GPT option is grayed out does that mean that it's already a GPT disk? – avorum Jan 20 at 22:29
This will never work if he is booting off of the 3TB disk. – Justin Jan 21 at 23:58

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