By Cherry / Last Updated September 13, 2017

Scenario: 3TB hard drive only shows 746GB on Windows Server 2003

“Hey!
I bought a new 3TB Hitachi HDD and installed it to my Server 2003. however, when I booted up and checked Disk Management, the new Hitachi hard drive only showed 746.39GB unallocated partition. Why? Is there anyone who can tell me how to use 3TB hard drive Server 2003 fully?”

“Could I make full use of 3TB hard drive on Windows Server 2003?”

Actually, there are many Windows Server 2003 users have met this kind of problem that 3TB hard drive on Server 2003 cannot be recognized full capacity. Part of users may asked “could I make full use of 3TB hard drive on Windows Server 2003?”. to figure out the answer, here you need to know more about Windows’ support for disks with capacity greater than 2TB.

About MBR and GPT: the MBR disk and GPT disk are all hard drive for storing data. Well, the MBR disk supports up to 2TB capacity while GPT disk supports hard drive that greater than 2TB capacity. In theory, a GPT disk can be up to 2^64 logical blocks in length. Logical blocks are commonly 512 bytes in size (see more details about difference between MBR and GPT).

Windows Server 2003 and GPT disk: actually, the maximum partition/disk size is a function of the operating system version. Windows XP and the original release of Windows Server 2003 have a limit of 2TB per physical disk, including all partitions. For Windows Server 2003 SP1, Windows XP x64 edition, and later versions, the maximum raw partition of 18 exabytes can be supported. Starting with Windows Server 2003 Service Pack 1, all versions of Windows Server can use GPT partitioned disks for data. While booting is only supported for 64-bit editions on Itanium-based systems.

Thus, you need to check about the version of your Windows Server 2003. if it is Windows Server 2003 Service Pack 1 and later version(s), you can make full use of 3TB hard drive on Windows Server 2003. However, many users still have the problem on Windows Server 2003 Service Pack 1 and later versions. How to fix it?

Fixed: can not full use 3TB hard drive on Windows Server 2003

If it is no problem with Windows Server 2003 operating system, then, you need to consider the two situations in the following content that may cause the problem cannot full use 3TB hard drive on Windows Server 2003.

Situation1: SATA ports

Some users may find that their 3TB hard drive only shows 746GB when it is connected to the computer via a USB enclosure. Why? Actually, there are some USB enclosures have 2TB limit, irrespective of the partition type. For this situation, you need to change the connected way to connect the external hard drive by SATA. Then, the 3TB hard drive may work normally on the Windows Server 2003.

Situation2: The 3TB hard drive is wrongly formatted as MBR

If there is no error with OS and connection, then, you need to check whether it’s wrong of your partition type. When the 3TB hard drive is formatted as MBR disk, you should convert MBR to GPT.

Convert MBR disk to GPT with Windows built in tool

1. You can convert the MBR disk to GPT with Windows Disk Management. Click Start, type diskmgmt.msc, press Enter to open Disk Management. To convert MBR disk to GPT via Windows Disk Management, you need to backup data first, then, delete all partitions on the MBR disk, and then, right click the MBR hard drive and select Convert to GPT Disk. Cause it can only convert an empty MBR to GPT. Otherwise, when you right click the disk, the Convert to GPT Disk option would be greyed out.

2. You can also make use of Diskpart, which allows you to convert MBR to GPT disk with command line. Click Start, type cmd, right click the program and choose Run as Administrator. It will pop out a command prompt. In the command prompt, you can start to convert MBR disk to GPT via Diskpart.

1>. Type diskpart, press Enter to open Diskpart command prompt.

2>. In the command prompt, type list disk, which will list all disk(s) in your hard drive.

3>. Then type select disk n, n refers to the disk number which you need to convert.

4>. Type clean, the data on the hard drive will be cleaned up so if there is any important data, back it up before cleaning.

5>. Type convert gpt.

6>. Wait till the progress reaches 100%, type exit to exit the program. Then type exit to exit CMD.

No matter Windows Disk Management or Diskpart, you can only convert an empty MBR disk to GPT. Is there any way that can convert MBR to GPT without losing data?

Convert MBR disk to GPT disk via AOMEI Partition Assistant

AOMEI Partition Assistant Server is a great disk management tool that allows you to convert between MBR and GPT disk without losing data on Windows Server 2003, 2008 (R2), 2012 (R2), and 2016. With this tool, you can even convert boot disk between MBR and GPT easily and safely. Here you can learn how to make use of AOMEI Partition Assistant to convert MBR to GPT without data loss. Besides, it is a great disk manager that can help you use 3TB hard drive on Windows Server 2003 more reasonable.

1. Install and launch AOMEI Partition Assistant. You can see its main interface that contains the basic situation of your hard disk(s). to convert MBR disk to GPT, here you should right click the MBR disk, select Convert to GPT Disk in the pop-up menu.

Convert to GPT

2. It will ask you if you are sure to convert MBR to GPT disk. Click OK->Yes.

Convert MBR to GPT

3. You will back to the main interface and you will see that the MBR disk has already changed into GPT disk. Click Apply at the toolbar to execute it.

Apply

Since your hard drive is GPT disk, you can use 3TB hard drive on Windows 2003 fully without the limitation of MBR disk.