Master boot record (MBR) disks use the standard BIOS partition table. GUID partition table (GPT) disks use extensible firmware interface (EFI). One advantage of GPT disks is that you can have more than four partitions on each disk. GPT is also required for disks larger than 2 terabytes.

You can change a disk from MBR to GPT partition style as long as the disk does not contain any partitions or volumes.

You cannot use the GPT partition style on removable media, or on cluster disks that are connected to shared SCSI or Fibre Channel buses that are used by the Cluster service.

Backup Operators or Administrator is the minimum membership required.

Note

Before you convert disks, close any programs that are running on those disks.

Changing a master boot record disk into a GUID partition table disk

To change a master boot record disk into a GUID partition table disk using the Windows interface

  1. Back up or move the data on the basic master boot record (MBR) disk you want to convert into a GUID partition table (GPT) disk.

  2. If the disk contains any partitions or volumes, right-click any volumes on the disk and then click Delete Partition or Delete Volume.

  3. Right-click the MBR disk that you want to change into a GPT disk, and then click Convert to GPT Disk.

To change a master boot record disk into a GUID partition table disk using a command line

  1. Back up or move the data on the basic master boot record (MBR) disk you want to convert into a GUID partition table (GPT) disk.

  2. Open a command prompt and type diskpart. If the disk does not contain any partitions or volumes, skip to step 6.

  3. At the DISKPART prompt, type list volume. Make note of the volume number you want to delete.

  4. At the DISKPART prompt, type select volume <volumenumber>.

  5. At the DISKPART prompt, type delete volume.

  6. At the DISKPART prompt, type list disk. Make note of the disk number of the disk that you want to convert to a GPT disk.

  7. At the DISKPART prompt, type select disk <disknumber>.

  8. At the DISKPART prompt, type convert gpt.

Important

You can only convert basic MBR disks without any partitions or volumes into a GPT disk. Back up your data and then delete all partitions or volumes before converting the disk.

Value Description

list volume

Displays a list of basic and dynamic volumes on all disks.

select volume

Selects the specified volume, where volumenumber is the volume number, and gives it focus. If no volume is specified, the select command lists the current volume with focus. You can specify the volume by number, drive letter, or mount point path. On a basic disk, selecting a volume also gives the corresponding partition focus.

delete volume

Deletes the selected volume. You cannot delete the system volume, boot volume, or any volume that contains the active paging file or crash dump (memory dump).

list disk

Displays a list of disks and information about them, such as their size, amount of available free space, whether the disk is a basic or dynamic disk, and whether the disk uses the master boot record (MBR) or GUID partition table (GPT) partition style. The disk marked with an asterisk (*) has focus.

select disk disknumber

Selects the specified disk, where disknumber is the disk number, and gives it focus.

convert gpt

Converts an empty basic disk with the master boot record (MBR) partition style into a basic disk with the GUID partition table (GPT) partition style.

Additional references

  • Change a Dynamic Disk Back to a Basic Disk
  • Change a GUID Partition Table Disk into a Master Boot Record Disk