The simple way to convert GPT disk partition to MBR disk partition

A disk is a separate physical hard drive. This will show you how to convert a GPT (GUID - Globally Unique Identifer) disk to a MBR (Master Boot Record) disk in Windows Disk Manager or in a command prompt. By default Windows uses MBR disks.

While all Windows can boot from a MBR disk, you can only boot from a GPT disk if you have a operating system (see below) that supports GPT and your motherboard has a EFI BIOS and is enabled. Windows 7 and Vista does support booting from a GPT disk.

The advantage of GPT disk

GPT disks can grow to a very large size. Break the 2TB limit of MBR disk. GPT disks allow an almost unlimited number of partitions. Each GPT partition has a unique identification GUID and a partition content type. And you can have more primary partitions. However, the Windows implementation restricts this to 128 partitions.

The limitation of MBR disk

MBR disk only support up to 2TB partition size and support only four primary partitions. If more partitions are wanted, you have to build a secondary structure known as extend partition, and then you can create logical partitions. MBR partitioning rules are complex and poorly specified.

Need of convert MBR/GPT

As known that MBR disk only support up to 2TB partition size, so when you have a disk which is MBR formatted and larger than 2TB, you could only use 2TB disk size among it, but the rest of it could not be used. Convert MBR disk to GPT disk is considerable necessary to make full use of the disk space. But note that the program prevent you from converting system disk, since GPT system disk only could boot from UEFI motherboard, but MBR system disk could not boot from this configuration.

In addition, since Windows 95/98/ME, Windows NT4, Windows 2000, Windows 2003 32-bit, Windows XP 32-bit version does not support GPT partitions. A GPT disk will display as GPT protective in these systems, thus you could not access the data until you convert them back to MBR disk. But note if you want to convert any larger than 2TB GPT disk back to MBR disk, you'd ensure that the data does not account for space more than 2TB

Differences Between MBR and GPT Disks:

• MBR disks are supported (readable) by all Windows operating systems.
• GPT disks are only supported (readable) by Windows server 2003 SP1 +, XP 64-bit, Vista, Windows 7, Windows Server 2008.
• MBR disks use the standard BIOS partition table.
• GPT disks use extensible firmware interface (EFI).
• MBR disks supports up to 2TB per single partition.
• GPT disks supports up to 256TB per single partition in Windows.
• MBR disks supports up to 4 Primary partitions or 3 Primary partitions and 1 Extended partition with up to 128 logical volumes in the extended partition.
• GPT disks supports up to 128 Primary partitions.
• Removable disks are MBR disks by default.
• Removable disks cannot be converted into a GPT disk.

There are two ways to convert GPT to MBR

1)Through Disk Management

1. Open the Control Panel (icons view), and click on the Administrative Tools icon, then close the Control Panel window.

2. Click on Computer Management in Administrative Tools, then close the Administrative Tools window.

3. If prompted by UAC, click on Yes.

4. In the left pane under Storage, click on Disk Management. (See screenshot below)

5. In the disk (ex: Disk 1) that you want to convert to a MBR disk, right click on each partition and volume on the disk and click on Delete Volume until the whole disk is unallocated space. (See screenshot above)

6. Right click on the disk (ex: Disk 1) that you want to convert to a MBR disk, and click on Convert to MBR Disk if available. (See screenshot below)

7. You can confirm that the disk is a MBR disk if you right click on the disk and it has Convert to GPT Disk instead now. (See screenshot below)

8. You can now create partitions on the now MBR disk if you like.

9. When done, close Disk Management.

Through a Command Prompt

1. Open an elevated command prompt.

A) Go to step 3.

OR

2. Open a command prompt at boot.

3. In the command prompt, type diskpart and press enter. (See screenshot above)

4. Type list disk and press enter.
NOTE: Make note of the disk number (ex: Disk 1) that you want to convert to a MBR disk.

5. Type select disk # and press enter.
NOTE: Substitute # with the actual disk number that you want to convert to a MBR disk. For example, select disk 1.

6. Do step 7 or 8 below for what you would like to do.

7. To Use the "Clean" Command to make Disk Unallocated
NOTE: This is the easiest method. It will wipe the disk clean all at once leaving it as unallocated space afterwards.

A) In the command prompt, type clean and press enter.
B) Go to step 9 below.

8. To Manually make Disk Unallocated
NOTE: This method has you manually delete each volume on the disk before converting the disk to MBR.

·         A) Type detail disk and press enter. If the disk does not have any volumes listed, then you can go to step 8E below.
NOTE: This will give you a list of all the volume numbers on the selected disk number that you will need to delete in steps 8B and 8C below.

B) Type select volume # and press enter.
NOTE: Substitute # with a volume number listed in step 8A. For example, select volume 3.

C) Type delete volume and press enter.

D) Repeat steps 8B and 8C for each volume # listed in step 8A until you have deleted all volume #'s.

E) When finished, type select disk # and press enter.
NOTE: You would use the same one from step 5 above. For example, select disk 1.

F) Go to step 9 below.

9. Type convert mbr and press enter.

10. Close the command prompt.

11. You can now create partitions on the now MBR disk if you like.
NOTE: Restart the computer if you did step 2 instead. 

For more

www.disk-partition.com

http://www.sevenforums.com