Disk Management shows new 4TB disk as 2TB despite using GPT

I have just added a 4TB disk to my Dell Precision T7500 workstation (running Windows 10 Pro, version 1809) and took the options in Disk Management to use GPT instead of MBR and to create a new Simple Volume. Despite this, the disk is displayed as having only 2TB of unallocated space. No other type of space is listed.

I've tried searching for a solution but all I have found so far are recommendations to use GPT, which I have already done. What am I missing here?

thomaseg1 said:

Can you post a screen image of what you see in Drive Management?
Make/model of disk. Internal or external drive?

It's a brand new Seagate ST4000DM006 Barracuda Pro 4TB internal drive, which is shown as Disk 0 in the Disk Management window.

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spunk said:

Press the Windows key+X and choose Powershell (Admin) or Command Prompt (Admin)
Here type Diskpart and press Enter. type the following Bold commands pressing Enter after Each one.

(ie) DISKPART >
ii) list disk
(ie) DISKPART > list disk
It now lists disk by number
you have to select the disk next with
iii) select disk <disk number>
(ie) DISKPART> Select Disk (disk number) = as listed in previous command. The selected disk now has an Asterisk next to it.
iv) clean (this erases all data on the Disk, so be sure you choose the correct one)
(ie) DISKPART> clean
v) convert gpt
vi) create partition primary
vii) format fs=ntfs quick
now for verification of disk status and free space type
v) list disk
the status should be "online" and free space should be "disk size"
‘vi)exit

I did exactly what you recommended, but as Disk 0 was already flagged as GPT, it made no difference to the size of the disk.

Both Size and Free were 2047GB at the start. After following your instructions, Size was 2047GB and Free was 0, which seemed a little odd, but Disk Management still shows 2047GB as 100% free.

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The Dell Precision T7500 workstation is a fairly old machine and the BIOS is dated 2008. Could that explain my problem?

spunk said:

Try the drive in another computer.
When you run the Clean command it wipes all partitions on the drive. Making it Unallocated Space. If the drive is already Initialized GPT , when run the Convert command, it will tell you it's already GPT. After running the commands, when you run the List Disk command, it will tell you the exact size of the drive. If it is still 2TB, then
The Drive may be falsely identified as a 4TB drive

All the space was already Unallocated, as I had not yet formatted the drive and given it a drive letter, so Clean didn't really do anything. I don't remember seeing any message that the drive was already GPT after running Convert, but the initial List Disk display clearly flagged the drive as GPT. I had also previously viewed the properties of that disk and this also confirmed that GPT applied.

It seems very unlikely that a Seagate Barracuda Pro drive would be wrongly labelled for size. My best guess is that either the BIOS or the motherboard of my rather old Dell workstation is unable to support drives bigger than 2TB.

I don't have any easy way to test this disk on anothr machine, as the only other computers I have access to are laptops.

thomaseg1 said:

Are you by chance running a 32bit version of windows? If so It is possible That there is a limit.
There are some cheap HDD enclosures That would allow through usb to connect to your laptop.
Hopefully, one of the Gurus here will have another idea.
I did find the page below on similar issue , I don't know If it will help but here it is.

https://www.dell.com/community/Deskt...B/td-p/4456769

I'm running 64-bit Windows 10.

Your link quotes a Dell T7500 user claiming to have a 4TB disk running. That is useful info. I will pursue this more when I get home this evening.

haggis999 said:

It's a brand new Seagate ST4000DM006 Barracuda Pro 4TB internal drive

There have been a few issues with GPT formatted Barracuda drives not showing full capacity (mostly 3TB showing 746GB). See here for example.

You could try as they suggest here and make sure your Intel RST drivers are up to date in case it is the same issue.