I've got a installation of Ubuntu running on a 3TB disk, during the installation I chose to use all of the available space (I don't remember if I checked LVM).

What I want to do now is shrink the partition to 2TB, and have 1TB as unallocated space , as eventually it will be used for storage for the main OS. I don't know how to do this, as it's the actively used partition, I tried to "Move/Resize" in Gparted, it let me go to 316mb then wouldent let me go further.

Could you please tell me:

1) How to shrink my hard disk to 2TB

2) How to save that unallocated space as storage, and "Mount" it to my Primary OS.

If you require further info, please ask.. Otherwise, please help!


I found a similar question here, but partition-growth centric.

Most important are the tools used. The drive must be unmounted, so to do this you could use a live CD.

Howtoforge hosts a howto, linked below: "If you want to resize partitions on production systems, please back up your data before, because it is possible you lose all your data if you don't calculate the size of your new partition correctly (especially when shrinking a partition)!"

A link about sizing partitions directly follows that disclaimer.

all of the commands must be run as super user, so, when you boot from the Live Disk, open the terminal and just run

sudo su

NOTE: If by main OS you mean Windows, know that when you install windows it will override the grub bootloader, so you may need to reinstall a (good) nother bootloader to boot your other 2TB of Ubuntu.


You can create a LiveUSB of Ubuntu and run gparted from it to resize your hard drive.

Since you have installed Ubuntu on your Primary partition, you won't be able to unmount it as long as you are running the operating system off it and, as a result, are unable to resize it.

  • Hi, I've tried that already after reading an article here, had the same result as running it live, it let me go to 316mb of memory then the "+" symbol greyed out. – Alex H Dec 21 '14 at 17:38

Your problem is related to the fact you can NOT change an active partition. Using a live dvd will not mount your partition giving you the possibility to shrink or enlarge primary partitions.

Shrinking is only possible for the amount of FREE space on the partition. And the more data is on the disk the longer it will take (since it will be moving files to space part of the new size). Also make sure to empty trash. If you never delete trash it piles up still using your disc.

  • I just finished trying what you suggested, unfortunately I still get the same problem, wont let me "Resize" anything past 316mb. If it helps at all, the Gparted does tell me that all the hard drive is full used, although I know I have about 2tb free space. Do you know what to do? – Alex H Dec 21 '14 at 19:26
  • Yes, most likely: trash. It won't count as used space but technically it is used. So delete it ;) – Rinzwind Dec 22 '14 at 7:16
  • But wouldent deleting the partition cause me to lose files?, what I'm trying to do is resize my operating system's partition (Which is 3tb) shrink it to 2tb, make 1tb for storage space on a new seperate partition so effectively stealing 1tb from the main operating system partition and move my personal files to that. I used the umount command in terminal and unmounted the device, gparted lost all sight of it then – Alex H Dec 22 '14 at 16:19
  • I am saying to delete trash from your system not to delete a partition. – Rinzwind Dec 22 '14 at 17:52
  • I have deleted everything I can off the system, there are a few GB of files that I need to transfer over, there's nothing in the rubbish bin. I have over 2TB of space on the hard disk that is not being used, but the Gparted says it's all used, this is what I can't work out, it wont let me take those 2+TB and make a new partition with it. – Alex H Dec 22 '14 at 19:53

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