I actually sell 2TB drive upgrades on eBay and may be the person @rallylc was referring to on page 12.
I've been upgrading and repairing Xbox One hard drives for about 6 months now and would like to provide more detail on the upgrade process than what's been in this thread lately.
I'd like to explain the pricing and why I can guarantee it will work.
First thing that doesn't work when using a non-standard drive (i.e. 2TB), defined as greater than 500GB or 1TB depending on your system is this thread's scripts to build a new drive from scratch. See page 9 of this thread.
Second thing that doesn't work is using a drive larger than 2TB. More on this later.
What does work, when wanting to use a non-standard drive (i.e. 2TB), is to clone (with Clonezilla and GParted) a working standard 500GB or 1TB drive depending on your system.
I plan on making a video of this soon, I just don't have a camera right now.
This works:
1. Pull out Xbox One HDD, connect via USB adapter to a laptop or desktop.
OPTIONAL: You may want to first connect the drive to a Windows machine and allow Windows to scan the partitions on the Xbox One HDD first. You can also scan the partitions using Clonezilla. This will avoid errors in the clone process later.
2. Insert or connect via a 2nd USB adapter the (empty) new 2TB HDD into the laptop or desktop.
3. Boot into Clonezilla live USB, disk to disk clone of 500GB -> 2TB drive using Clonezilla. Google clonezilla-live-2.4.5-23-amd64.zip and I recommend having at least a 16GB USB flash drive.
4. Reboot into a GParted live USB, start GParted. It will complain about some stuff not being aligned/all drive space not being used in the GPT, I clicked "Fix" (tried it without it at first but partitions wouldn't resize). For this I used LinuxLive USB Creator 2.9.4.exe, ubuntu-15.10-desktop-amd64.iso and a 16GB USB flash drive.
5. Move the free space at the end of the 2TB drive next to the "User Data" partition. To do this you need to first move 3 partitions.
Partition 5 'System Update 2', then partition 4 'System Update', and partition 3 'System Support'.
a. In GParted select the partition then click Resize/Move
b. Change "Free space following (MiB)" to 0
c. Click "Free space preceding (MiB)" and let the number auto update
d. Finally click the Resize/Move button in the bottom right
You will need to do this 3 times and will have to apply the changes. I would move the partitions first then do the next step.
6. Now you will extend the 'User Content' partition to the max size. This is the number you will actually see when checking the storage on the Xbox One.
a. In GParted select partition 2 'User Content' then click Resize/Move
b. Select "New size (MiB)" and change it to the "Maximum size" number above, both the "Free space preceding (MiB)" and "Free space following (MiB)" should be 0.
c. Finally click the Resize/Move button in the bottom right
7. Shut down laptop or desktop and remove freshly-minted Xbox One drive. You should be able to put this in to your Xbox One and have it boot straight away. Be sure to reconnect all the wires before testing.
This process works and you should now have a 1.7TB Xbox One drive.
For reference, here are the valid default 500GB HDD GParted sizes:
/dev/sda1 = 41984 MiB
/dev/sda2 = 373760 MiB
/dev/sda3 = 40960 MiB
/dev/sda4 = 12288 MiB
/dev/sda5 = 7168 MiB
I've found that drives larger than 2TB do not work, but maybe someone has found a way to make this work.
GParted is the only tool that can deal with Xbox One parition resizing. The partions are NTFS partitions and can be seen on Windows but resizing tools on Windows see the partition type as "Other" and not NTFS.
When moving the 5th partion 'System Update 2' on a 4TB drive you cannot set "Free space following (MiB)" to lower than 1712000 MiB = 1.63 TiB. Basically you need to leave this space unallocated at the end of the drive.
If you don't, the drive will produce an E200 error on the Xbox One. Meaning partion 4 'System Update' is missing or corrupt. Also, GParted crashes after completing the move.
Lastly, eBay pricing for a 2TB upgrade.
The 2TB drive costs about $90 on Amazon, return shipping is about $15. eBay takes 5% or $6. This means the lowest you could charge is $111 to not make a profit.
You need to have the equipment to clone a working 500GB or 1TB drive which mean you need the original drive.
Since you need the original drive it is best to send the entire system so that I can verify the process worked.
In addition, I'll swap out LEDs of up to 2 controllers as well as the system.
Hope this helps someone upgrade their Xbox One internal drive to 2TB and remember do not use "Restore factory defaults" after this process as it will return your drive to 500GB or 1TB depending on your system.