GPT is the GUID Partition Table that replaces MBR on UEFI systems. Every GPT disk has a protective MBR with one type 0xEE partition so old tools never see the disk as empty. Windows limits GPT to 128 partitions and MBR has four entries. Convert with MBR2GPT to preserve data or with DiskPart clean and convert gpt on an empty disk.
Disk Management or a partition tool shows a GPT Protective Partition and many users fear that the disk is damaged. It is a normal structure of every GPT disk.
Facts follow the Microsoft pages Windows and GPT FAQ and UEFI and GPT partitions and MBR2GPT. DiskPart samples are not executed in a test machine.
What is a GPT Protective Partition?
Microsoft states that all GPT disks contain a protective MBR. This MBR stores one type 0xEE partition that spans the disk.
Its purpose is protection from legacy tools like MS-DOS FDISK. Those tools see a GPT disk as one encompassing and possibly unrecognized partition and not as an unpartitioned disk.
How does GPT Compare With MBR?
| Item | MBR | GPT |
|---|---|---|
| Partition entries | Four. More partitions need an extended partition | Windows limits GPT to 128 |
| Partition size | Limited by the older layout | Up to 18 exabytes per partition |
| Boot on UEFI | Not allowed for the boot disk | Required for the boot disk |
| Data disks | Allowed | Allowed |
Microsoft states that UEFI systems need the boot partition on a GPT disk. Other disks can use MBR or GPT.
Which Partitions does a UEFI GPT Disk Need?
- EFI System Partition. Holds boot files and uses FAT32. One per system.
- Microsoft Reserved Partition. Exists on every GPT disk and cannot store user data.
- Windows partition. NTFS volume with the operating system.
- Recovery partition. Placed after the Windows partition.
Partition sizes differ between Microsoft pages and Windows versions so check the current page before you plan a layout.
How do You Convert MBR to GPT?
- Backup all data first.
- Validate the system disk with
mbr2gpt /validate. - Convert with
mbr2gpt /convertafter all checks pass. - Switch firmware to UEFI mode because the converted disk boots only in UEFI mode.
MBR2GPT converts a system disk without modifying or deleting data. It cannot convert non system disks and it needs no more than three primary partitions. Microsoft states the tool cannot undo the conversion.
DiskPart creates a GPT disk only on an empty disk. This sample erases all data on disk 1.
list disk
select disk 1
clean
convert gptNever make a sector by sector copy of a GPT disk. Disk and partition GUIDs then stop being unique.
For related disk work see how to delete hard disk data permanently and how to free up disk space in Windows.
Frequently Asked Questions
What is a GPT Protective Partition?
It is the type 0xEE partition in the protective MBR that every GPT disk contains.
Does GPT Protective Partition Mean the Disk is Damaged?
No. Microsoft states all GPT disks contain a protective MBR.
How Many Partitions Fit on a GPT Disk in Windows?
Windows limits a GPT disk to 128 partitions.
Can I Convert MBR to GPT Without Data Loss?
Yes for a system disk. MBR2GPT converts without modifying or deleting data. Backup first anyway.
Does DiskPart Convert Keep My Data?
No. DiskPart creates GPT only on an empty disk so you must clean the disk first.
Key Takeaways
- Every GPT disk has a protective MBR with a type 0xEE partition.
- Protective partitions are normal and not damage.
- Windows limits GPT to 128 partitions.
- MBR2GPT preserves data on system disks.
- DiskPart clean erases all data before convert gpt.
Sources and References
Facts follow Microsoft pages.
- Windows and GPT FAQ (Microsoft Learn) learn.microsoft.com
- UEFI/GPT-based hard drive partitions (Microsoft Learn) learn.microsoft.com
- MBR2GPT.EXE (Microsoft Learn) learn.microsoft.com