There are 2 partition styles most
commonly used to partition disk, MBR and GPT. They are different
slightly in supported partition amounts, disk capacity, OS compatibility
and boot mode. For example, GPT can support disk larger than 2TB but
MBR partition style cannot. And this is why your 4TB hard drive only
shows 2TB.
So, to restore all the capacity of the hard drive, you
need to convert the MBR disk to GPT disk. In the following content, let
me walk you through how to perform such a conversion (Windows 11 only
supports UEFI, so you need to convert MBR to GPT).
1. Convert 4TB drive to GPT with Diskpart (data loss)
There
is a built-in tool called Diskpart, which can convert 4TB hard drive to
GPT with several lines of command. Here are the detailed steps.
✍Note:
this method needs to clean your disk before converting, so if it is not
a new hard drive or has important data on it, you have to back up the
disk beforehand.
Step 1. Press “WIN+R”, type “CMD” and press Enter to open the command prompt. Then, input
"diskpart" and hit Enter.
Step 2. Type the following commands, remember press Enter after you input each one.
list disk
select disk n (n means the drive letter, replace it with your 4TB drive letter)
clean (clear all partitions on the selected disk)
convert gpt
When the “DiskPart successfully converted the selected disk to GPT format” shows on the screen, type “exit” and press “Enter” to leave the program, and check if the rest of the capacity is restored.
Source: https://www.diskpart.com/articles/4tb-drive-only-shows-2tb-1984.html
