On GPT disks that are used to boot the Windows operating system, the Extensible Firmware Interface (EFI) system partition is the first partition on the disk, followed by the Microsoft Reserved partition. GPT disks that are used only for data storage do not have an EFI system partition, in which case the Microsoft Reserved partition is the first partition.

Windows does not mount Microsoft Reserved partitions. You cannot store data on them and you cannot delete them.

A Microsoft Reserved partition is required on every GPT disk. The size of this partition depends on the total size of the GPT disk. The size of the GPT disk must be at least 32 MB to create a Microsoft Reserved partition.

A basic GPT disk must be selected for this operation to succeed. Use the select disk command to select a basic GPT disk and shift the focus to it.