Using and Converting MBR and GPT Disks

Tasks for using MBR and GPT disks are similar but not necessarily identical. On an x86-based computer, you can use MBR for booting or for data disks and GPT only for data disks. On an Itanium-based computer, you can have both GPT and MBR disks, but you must have at least one GPT disk that contains the ESP and a primary partition or simple volume that contains the operating system for booting.

Partitions and volumes on MBR and GPT disks can be formatted using FAT, FAT32, and NTFS. When you create partitions or volumes in Disk Management, you have the opportunity to format the disk and assign it a drive letter or mount point as part of the volume creation process. Although Disk Management lets you format the partitions and volumes on MBR disks using FAT, FAT32, and NTFS, you can format partitions and volumes on GPT disks using only NTFS. If you want to format GPT disks by using FAT or FAT32, you must use either the Format or DiskPart command at the command prompt. Further, keep in mind that you can use Windows Server Backup to back up only NTFS partitions. If your server has partitions using other formats and you want to back them up, you'll need to use a different backup utility.

You can change partition table styles from MBR to GPT or from GPT to MBR. Changing partition table styles is useful when you want to move disks between x86-based computers and Intel Architecture 64 (IA-64)-based computers or you receive new disks that are formatted for the wrong partition table style. You can convert partition table styles only on empty disks, however. This means the disks must either be new or newly formatted. You could, of course, empty a disk by removing its partitions or volumes.

You can use both Disk Management and DiskPart to change the partition table style. To use Disk Management to change the partition style of an empty disk, start Computer Management from the Administrative Tools menu or by typing compmgmt.msc at the command line, expand the Storage node, and then select Disk Management. All available disks are displayed. Right-click the disk to convert in the Graphical View, and then click Convert To GPT Disk or Convert To MBR Disk as appropriate.

To use DiskPart to change the partition style of an empty disk, invoke DiskPart by typing diskpart, and then selecting the disk you want to convert. For example, if you want to convert disk 3, type select disk 3. After you select the disk, you can convert it from MBR to GPT by typing convert gpt. To convert a disk from GPT to MBR, type convert mbr.