Windows 10 Gpt Iso Download

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Quick Guide to Install Windows 10 on GPT:

  1. 1. Connect a Windows 10 USB to your PC and boot the PC.
  2. 2. Boot the system into the BIOS (for example, using F2 or the Delete key)
  3. 3. Locate the Boot Options Menu.
  4. 4. Set Launch CSM to Enabled.
  5. 5. Set Boot Device Control to UEFI Only.
  6. 6. Set Boot from Storage Devices to UEFI driver first.
  7. 7. Save your changes and restart the system.
  8. 8. Reboot the system and install Windows 10 on GPT.

On EFI systems, Windows can only be installed to GPT disks” during OS installation. Three free MBR to GPT converters for Windows 10/8/7. Generally speaking, there are 3 different free converters for Windows users to convert MBR to GPT: Disk Management, Diskpart and a third-party partition manager tool. Download GPT fdisk for free. GPT fdisk is a disk partitioning tool loosely modeled on Linux fdisk, but used for modifying GUID Partition Table (GPT) disks. The related FixParts utility fixes some common problems on Master Boot Record (MBR) disks.

Are you looking for an efficient way to install Windows 10 on GPT disk without any issues? Check out the quick navigation, and follow tutorials below in each part, you'll successfully install Windows 10 on GPT partition on your own:

Download Windows 10 Disc Image (ISO File) Before updating, please refer to the Windows release information status for known issues to confirm your device is not impacted. On this page, we included the whole process to guide you to install Windows 10 on a GPT disk partition. To complete the whole process, you need to execute the following operations: #1. Prepare GPT Disk #2. Download Windows 10 ISO and Create Windows Installation Media to USB #3. Configure PC Boot Mode to UEFI, and Boot from USB #4.

Workable SolutionsStep-by-step Troubleshooting
Part 1. Prepare GPT Disk for Windows InstallationConfirm computer supports UEFI boot mode > Prepare GPT disk ready for Windows 10 installation...Full steps
Part 2. Install Windows 10 on GPT Disk

Step 1. Connect Windows installation USB to PC and reboot it into BIOS;

Step 2. Set PC boot from USB and install Windows 10 on GPT...Full steps

Part 3. Protect GPT Partition DataCreate a regular backup of vital data > Execute operation carefully > Clean up virus...Full steps

Can I Install Windows 10 on GPT Partition?

Don't worry if you are having the following problems while trying to install Windows 10 on a GPT disk:

Case 1 - Your computer reports that it can't install Windows 10 on GPT partition with the error message 'Windows cannot be installed on this disk. The selected disk is of the GPT partition style'.

Case 2- 'I have upgraded from Windows 8.1 to Windows 10, and now I wish to do a clean install. Then I burnt Windows 10 to a disk. When I was trying to do it, I get a problem with an error message 'Windows cannot be installed on this disk. The selected disk is of the GPT partition style.' Is there any way to fix the issue and install Windows 10 on GPT partition with success?'

The reason why you get this error is that your PC is booted in UEFI mode, but your hard drive is not configured for UEFI mode. On the following, we'll cover the complete process for you to follow and install Windows 10 on GPT disk without losing any data. No error message like 'Windows cannot be installed' error will be prompted.

Let's get started to install Windows 10 on your computer now.

Part 1. Prepare GPT Disk for Windows Installation

Applies to: Prepare GPT disk for Windows 10 installation.

To obtain a successful Windows 10 installation process, here are two things that you need to get them done in advance:

#1. Confirm Computer Supports UEFI Boot Mode

Note that if the motherboard of your computer doesn't support UEFI, it only supports BIOS. It won't allow you to install Windows 10 on a GPT partition.

Therefore, you should first check out and confirm if your computer supports UEFI boot mode:

  • Boot the PC and press the key (Esc, F2, F8, F12, Del, or another key) to enter the firmware or boot menu.
  • On the boot menu, check if the computer supports UEFI boot mode.

If the motherboard only supports Legacy BIOS boot mode, we are sorry that you have to stop here. As your computer doesn't support UEFI boot mode, you can't install Windows 10 on GPT disk which requires UEFI boot mode.

If you see the UEFI boot option in BIOS as shown below, exit BIOS. And you can continue with the following steps.

Also read:Fix UEFI Boot Errors in Windows 10/8/7

#2. Prepare GPT Disk for Windows 10 Installation

It's vitally important that you make the target disk ready before installing Windows 10 to a GPT partition. Here are the tips that you can follow to make the disk ready:

As the way to set a disk ready varies, we suggest you follow the right way to configure your disk based on your own needs.

# For a New Disk - Initialize to GPT

1. Install the new disk to your computer. You may refer to How to Install a New HDD/SSD for help.

2. Configure and initialize your disk to GPT

If you are an experienced user, you can directly open Disk Management and initialize the disk to GPT.

If you have 0 experience in disk management, we suggest you download reliable partition manager software - EaseUS Partition Master and follow the steps here to initialize your new disk to GPT:

Step 1: Download the software

Download EaseUS Partition Master. Connect the hard drive or SSD to PC.

Step 2: Initialize your HDD/SSD

Right-click the target HDD or SSD and select 'Initialize to MBR' or 'Initialize to GPT' accordingly.

Fig 1. Initialize to MBR:

Fig 2. Initialize to GPT:

Step 3: Apply the operation

A pending operation of initializing disk to MBR or GPT disk will be added. Execute the operation and click 'Apply'.

# For an Old Disk - Convert Disk to GPT, Backup Data

1. Convert Disk to GPT

If your disk is with the MBR partition style, you need to convert it to GPT disk. And EaseUS Partition Master can directly convert MBR disk to GPT disk without data loss.

Step 1. Download and launch EaseUS Partition Master on your Windows computer.

Step 2. Right-click the MBR disk that you want to convert and choose 'Convert to GPT'.

Step 3. After that, find and click the 'Execute 1 Operation' button on the toolbar and choose 'Apply' to start the conversion. You need to restart your device to enable this change.

2. Backup Vital Data

If you have vital data saved on the old drive, we suggest you back up the data to another disk or an external hard drive first.

3. Format GPT Partition

It's suggested that you format the used target GPT partition (with at least 20GB capacity) in advance so as to install Windows 10 on it.

If you don't format the GPT partition, all files on the partition will be reserved, which will take huge space on your system C drive. It's obviously not a smart choice.

After that, you can now move to Part 2 on this page and start installing Windows 10 on the GPT disk.

Part 2. How to Install Windows 10 on GPT Partition

Applies to: Guide you install Windows 10 on GPT disk partition.

Things could be easier if you already have Windows 7 or 8.1 installed, you can directly upgrade to Windows 10.

But if you are looking for a to installing or reinstall a fresh version of Windows 10 on a GPT partition, you are in the right place. Follow the steps below to learn how to install Windows 10 on a GPT partition:

Step 1. Create a Windows 10 installation media on an empty USB (min 8GB).

You need to prepare:
①. An empty USB (8GB min)
②. Download Windows 10 ISO file
③. Get a Windows product key (activate after the installation) before you start the steps.

Step 2. Connect the Windows 10 installation USB to your PC and boot the system into BIOS.

Restart PC and press the Esc, F2, F8, F12, Del, or another key to enter the BIOS boot menu.

Step 3. Locate the boot options menu and enable the UEFI mode.

  • Set Launch CSM to Enabled. If CSM is set to Disabled, you can skip to Step 4 below
  • Set Boot Device Control to UEFI Only
  • Set Boot from Storage Devices to UEFI driver first

Step 4. Set the USB UEFI OS Boot option is at the top of the Boot Priority List.

Step 5. Save your changes and restart the system to start installing Windows 10 on the GPT disk.

1. Choose which media to use - USB flash drive.

2. Click 'Install Now', then set the language and other preferences.

3. Skip entering a product key and select 'Install Windows only'.

Select to install Windows 10 to the GPT partition, wait for the process to complete.

4. Your computer may restart several times during this process. And the installation may take several minutes, about half an hour or more, just wait patiently.

Step 6. When you complete the installation, reboot the PC and enter BIOS.

Set the computer to boot from the new GPT disk with Windows 10. Save the changes and restart the PC.

Step 7. Confirm that Windows 10 is installed on a GPT partition.

After Windows 10 finally boots up, you can now check up if Windows 10 is installed on your GPT disk partition by following tips here:

  • Boot into Windows > Open 'Disk Management'.
  • You see three partitions including the EFI System Partition.
  • Right-click the disk > select 'Properties > 'Volumes'. Here you can confirm the Partition style:

Step 7. Activate Windows 10 with Product Key

After the Windows installed, you'll be asked to activate it with your product key.

Go to Settings > Update & Security > Activation > Enter a product key to enjoy full features of Windows 10 on your PC:

After this, you can enjoy all the full features in Windows 10 on your computer. It will make your life and work easy and enjoyable.

Part 3. How to Protect Your GPT Partition Data (Extra Tips)

If you have data on your GPT partition, this part would do you a great favor. Here's a list of tips that you can follow to protect your data efficiently:

  1. 1. Create a regular backup of vital data

If you often make changes to your disk data, it's important that you create a regular backup of vital data on your GPT disk partition.

To ease your burden, you can try free back up software - EaseUS Todo Backup Free to create a full back up your data every day by creating an automatic backup plan.

Refer to: Schedule Backup Software for Automatic Backup

  1. 2. Delete files, format drive partitions, wipe a disk with awareness

It's essential that you should always be careful with operations that will remove data and files on your computer. For example, you need to make sure that you don't delete wrong files, format a false storage device, or wipe a wrong hard drive or partition.

  1. 3. Run antivirus software to clean up virus, malware regularly

As we know that viruses or malware infection may cause unexpected data loss issues on your storage devices, like GPT disk partition. We suggest you always install reliable antivirus software to scan and clean up your computer and devices regularly.


On this page, we included the whole process to guide you to install Windows 10 on a GPT disk partition. To complete the whole process, you need to execute the following operations:

  1. #1. Prepare GPT Disk
  2. #2. Download Windows 10 ISO and Create Windows Installation Media to USB
  3. #3. Configure PC Boot Mode to UEFI, and Boot from USB
  4. #4. Start and Finish Installing Windows 10 on the GPT Disk Partition
  5. #5. Reboot PC and Set Windows to Boot from New GPT Partition
  6. #6. Activate Windows 10

During the process, If you are faced with 'The selected disk is the GPT partition style' error, you can refer to Part 1 to convert the disk to GPT with the help of reliable partition manager software and continue installing Windows 10.

By the way, to avoid data loss, it is also of great importance to create a regular backup of your GPT partition data.

People Also Ask

If you have more questions about Windows installation, check out the questions and answers as listed below:

1. Can you install Windows 10 on GPT?

Normally, as long as your computer motherboard and bootloader support UEFI boot mode, you can directly install Windows 10 on GPT.

If the setup program says that you cannot install Windows 10 on the disk because the disk is in GPT format, it is because you have UEFI disabled. The solution is to enter BIOS (by pressing a key during startup, either F1 or F10-F12 depending on your computer model), find the option to enable UEFI.

Then you can continue installing Windows 10 on the GPT disk.

2. Should I install Windows 10 on MBR or GPT?

To use MBR to GPT to install Windows 10 is highly depended on your disk capacity and the motherboard on your computer:

  • 2TB or smaller Disk: Use it as MBR to install Windows 10.
  • Disk larger than 2TB: Use it as GPT to install Windows 10.
  • BIOS only supports Legacy boot mode: Install Windows 10 on MBR.
  • BIOS supports UEFI boot mode, and disk is larger than 2TB: Install Windows 10 on GPT.

Also read:MBR VS GPT

3. How many partitions are created when you install Windows 10 on a GPTdisk?

  • On a brand new GPT: Windows will automatically generate two partitions on your disk - a boot partition, and a system C drive partition.
  • On a used GPT disk: Windows will be installed on a selected partition. No further partitions will be generated.

If you want to manually create more partitions, you can manage GPT partitions on your own. In short, GPT disk support to create up to 128 partitions.


Answers to frequently asked questions about the GUID Partition Table (GPT).

This version of the Windows and GPT FAQ applies to Windows 10 and Windows Server 2016. For a previous version of this FAQ, see Windows and GPT FAQ on MSDN.

Since the introduction of the personal computer, the data storage area on a hard disk has been divided into smaller areas called sectors. These sectors are grouped into partitions creating separate volumes, or 'drives' on a disk. The partitions were organized using a scheme called the Master Boot Record (MBR). The MBR is a table of disk locations, or addresses, along with a certain length, of each of the partitions present on the disk. The MBR itself occupies a small amount of the disk and is read during the boot phase to determine where to locate the operating system to boot into. The MBR information is also used by the operating system as a map of the volumes present on the disk.

Eventually, data density for disks became too large for the MBR scheme to account for all the available data locations. Also, the layout, or format, of the MBR was designed for early computers and not flexible enough to accommodate newer disk configurations. A new partitioning method was needed so the GUID Partition Table (GPT) partitioning scheme was created.


What a GPT disk is

The GUID Partition Table (GPT) was introduced as part of the Unified Extensible Firmware Interface (UEFI) initiative. GPT provides a more flexible mechanism for partitioning disks than the older Master Boot Record (MBR) partitioning scheme that was common to PCs.

A partition is a contiguous space of storage on a physical or logical disk that functions as if it were a physically separate disk. Partitions are visible to the system firmware and the installed operating systems. Access to a partition is controlled by the system firmware before the system boots the operating system, and then by the operating system after it is started.

What is wrong with MBR partitioning

MBR disks support only four partition table entries. For more than four partitions, a secondary structure known as an extended partition is necessary. Extended partitions can then be subdivided into one or more logical disks.

Windows creates MBR disk partitions and logical drives on cylinder boundaries based on the reported geometry, although this information no longer has any relationship to the physical characteristics of the hardware (disk driver or RAID controller). Starting with Windows Vista and Windows Server 2008, more logical boundaries are selected when the hardware provides better hints at the true cache or physical alignment. Because this partition information is stored on the drive itself, the operating system is not dependent on the alignment.

MBR partitioning rules are complex and poorly specified. For example, does cylinder alignment mean that each partition must be at least one cylinder in length? An MBR partition is identified by a two-byte field, and coordination is necessary to avoid collision. IBM originally provided that coordination, but today there is no single authoritative list of partition identifiers.

Another common practice is using partitioned or 'hidden' sectors to hold specific information by using undocumented processes and results in problems that are difficult to debug. In the past, vendor-specific implementations and tools were released to the public, which made support difficult.

Why we need GPT

GPT disks allow for growth. The number of partitions on a GPT disk isn't constrained by temporary schemes such as container partitions as defined by the MBR Extended Boot Record (EBR). The GPT disk partition format is well defined and fully self-identifying. Data critical to platform operation is located in partitions and not in unpartitioned or 'hidden' sectors. GPT disks use primary and backup partition tables for redundancy and CRC32 fields for improved partition data structure integrity. The GPT partition format uses version number and size fields for future expansion.

Each GPT partition has a unique identification GUID and a partition content type, so no coordination is necessary to prevent partition identifier collision. Each GPT partition has a 36-character Unicode name. This means that any software can present a human-readable name for the partition without any additional understanding of the partition.

Where to find the specification for GPT disk partitioning

Chapter 5 of the Unified Extensible Firmware Interface (UEFI) specification (version 2.3) defines the GPT format. This specification is available at

The GPT format for basic disks

Basic disks are the most commonly used storage types with Windows. 'Basic disk' refers to a disk that contains partitions, such as primary partitions and logical drives, usually formatted with a file system to become a volume for file storage.

The protective MBR area on a GPT partition table exists for backward compatibility with disk management utilities that operate on MBR. The GPT header defines the range of logical block addresses that are usable by partition entries. The GPT header also defines its location on the disk, its GUID, and a 32-bit cyclic redundancy check (CRC32) checksum that is used to verify the integrity of the GPT header. Each entry in the GUID partition table begins with a partition type GUID. The 16-byte partition type GUID, which is similar to a System ID in the partition table of an MBR disk, identifies the type of data that the partition contains and identifies how the partition is used, for example, whether it is a basic disk or a dynamic disk. Note that each GUID partition entry has a backup copy.

For more information about basic disks, see Basic and Dynamic Disks.

The GPT format for dynamic disks

Dynamic disks were first introduced with Windows 2000 and provide features that basic disks don't, such as the ability to create volumes that span multiple disks (spanned and striped volumes) and the ability to create fault-tolerant volumes (mirrored and RAID-5 volumes). Dynamic disks can use the MBR or GPT partition styles on systems that support both. For more information about dynamic disks, see Basic and Dynamic Disks.

UEFI requirements for a GPT disk

GPT disks are self-identifying. All the information needed to interpret the partitioning scheme of a GPT disk is completely contained in structures in specified locations on the physical media.

How big can a GPT disk be

In theory, a GPT disk can be up to 2^64 logical blocks in length. Logical blocks are commonly 512 bytes in size.

The maximum partition (and disk) size depends on the operating system version. Windows XP and the original release of Windows Server 2003 have a limit of 2TB per physical disk, including all partitions. For Windows Server 2003 SP1, Windows XP x64 edition, and later versions, the maximum raw partition of 18 exabytes can be supported. (Windows file systems currently are limited to 256 terabytes each.)

How many partitions a GPT disk can have

The specification allows an almost unlimited number of partitions. However, the Windows implementation restricts this to 128 partitions. The number of partitions is limited by the amount of space reserved for partition entries in the GPT.

Whether a disk can be both GPT and MBR

No. However, all GPT disks contain a Protective MBR.

Protective MBR

The Protective MBR, beginning in sector 0, precedes the GPT partition table on the disk. The MBR contains one type 0xEE partition that spans the disk.

Why the GPT has a Protective MBR

The Protective MBR protects GPT disks from previously released MBR disk tools such as Microsoft MS-DOS FDISK or Microsoft Windows NT Disk Administrator. These tools are not aware of GPT and don't know how to properly access a GPT disk. Legacy software that does not know about GPT interprets only the Protected MBR when it accesses a GPT disk. These tools will view a GPT disk as having a single encompassing (possibly unrecognized) partition by interpreting the Protected MBR, rather than mistaking the disk for one that is unpartitioned.


Why a GPT-partitioned disk would appear to have an MBR on it

This occurs when you use an MBR-only-aware disk tool to access the GPT disk. For more information, see the following sections:

  • How a disk can be both GPT and MBR
  • Protective MBR
  • Why the GPT has a Protective MBR

Windows disk support

Whether Windows XP x64 can read, write, and boot from GPT disks

Windows XP x64 Edition can use GPT disks for data only.

Whether the 32-bit version of Windows XP read, write, and boot from GPT disks

No. The 32-bit version will see only the Protective MBR. The EE partition will not be mounted or otherwise exposed to application software.

Whether the 32- and 64-bit versions of Windows Server 2003 read, write, and boot from GPT disks

Starting with Windows Server 2003 Service Pack 1, all versions of Windows Server can use GPT partitioned disks for data. Booting is only supported for 64-bit editions on Itanium-based systems.

Can Windows Vista, Windows Server 2008, and later read, write, and boot from GPT disks

Yes, all versions can use GPT partitioned disks for data. Booting is only supported for 64-bit editions on UEFI-based systems.

Can Windows 2000, Windows NT 4, or Windows 95/98 read, write, and boot from GPT

No. Again, legacy software will see only the Protective MBR.

Moving a GPT disk to another computer

You can move, or migrate,


Removable media without either GPT or MBR formatting is considered a 'superfloppy'. The entire media is treated as a single partition.

The media manufacturer performs any MBR partitioning of removable media. If the media has an MBR, only one partition is supported. There is little user-discernible difference between MBR-partitioned media and superfloppies.

Examples of removable media include floppy disk drives, JAZ disk cartridges, magneto-optical media, DVD-ROM, and CD-ROM. Hard disk drives on external buses such as SCSI or IEEE 1394 are not considered removable.

What is the default behavior of Windows XP 64-Bit Edition Version 2003 when partitioning media?

For Windows XP 64-Bit Edition Version 2003 only (for Itanium-based systems), fixed disks are partitioned by using GPT partitioning. GPT disks can be converted to MBR disks only if all existing partitioning is first deleted, with associated loss of data.

The default behavior of the 32-bit version of Windows XP, Windows Server 2003 and Windows XP x64 when partitioning media

Only MBR disks can be used.

Mapping a drive letter in the operating system to a partition in UEFI firmware

There is no inherent mapping between drive letter and partition that can be used to determine one from the other. A basic data partition must be identified by its partition GUID.

Creating an ESP partition

ESP partitions can be created by using the UEFI firmware utility Diskpart.efi or the Windows command line utility Diskpart.exe.

Changes on a partition

You shouldn't directly change any partition header entry. Don't use disk tools or utilities to make alterations or changes.

Supported partitioning on detachable disks

Detachable disks are typically expected to migrate between computers or simply to be unavailable to the operating system at times. Examples of detachable disks are USB disks, which can be easily disconnected by the end-user. Windows XP supports only MBR partitioning on detachable disks. Later versions of Windows support GPT partitions on detachable disks.

For more about removable media, see the following questions:

  • Removable media
  • Superfloppy

Windows GPT required partitions: EFI System Partition

The Extensible Firmware Interface System Partition (ESP)

The ESP contains the NTLDR, HAL, Boot.txt, and other files that are needed to boot the system, such as drivers. The Partition GUID defines the ESP:

DEFINE_GUID (PARTITION_SYSTEM_GUID, 0xC12A7328L, 0xF81F, 0x11D2, 0xBA, 0x4B, 0x00, 0xA0, 0xC9, 0x3E, 0xC9, 0x3B)

GPT Disks and ESPs

No, MBR disks can also have ESPs. UEFI specifies booting from either GPT or MBR. The ESP on an MBR disk is identified by partition type 0xEF. However, Windows does not support booting UEFI from MBR disks or 0xEF partitions.

The size of the ESP

The ESP is approximately 100MBs.

Two ESPs on a single disk

Such a configuration shouldn't be created, and is not supported in Windows.

Two ESPs on two different disks

ESP partitions can be replicated for high-availability configurations. Replication must be done manually and the contents must be synchronized manually when using software volumes. Hardware vendors may provide additional solutions for high availability. ESP partitions cannot be mirrored.

What Microsoft places in the ESP

Microsoft places the HAL, loader, and other files that are needed to boot the operating system in the ESP.

ESP placement on the disk

The ESP should be first on the disk. The primary benefit to placing the ESP first, is that it is impossible to span volumes when the ESP is logically between the two data partitions that you are attempting to span.

System or device manufacturer additions to the ESP

The ESP should only include files that are required for booting an operating system, platform tools that run before operating system boot, or files that must be accessed before operating system boot. For example, files that are required for performing pre-boot system maintenance must be placed in the ESP.

Other value-add files or diagnostics used while the operating system is running should not be placed in the ESP. It is important to note that the space in the ESP is a limited system resource; its primary purpose is to provide storage for the files that are needed to boot the operating system.

System manufacturer placement for files such as platform diagnostics or other value-added files

The preferred option is for system manufacturers to place value-add contents in an OEM-specific partition. Just like MBR OEM partitions, the contents of GPT OEM (or other unrecognized) partitions are not exposed (given drive letters or returned in volume lists). Users are warned that deleting the partition can cause the system to fail to operate. An OEM-specific partition should be placed before the MSR and after any ESP on the disk. Although not architectural, this placement has the same benefits as placing the ESP first. For example, it is also impossible to span volumes when an OEM-specific partition is logically between the two data partitions that you are attempting to span.

Placement in the ESP is an option for applications or files that execute in the pre-operating system boot environment. However, the ESP is architecturally shared space and represents a limited resource. Consuming space in the ESP should be considered carefully. Files that are not relevant to the pre-operating system boot environment should not be placed in the ESP.

Microsoft Reserved Partition (MSR)

The Microsoft Reserved Partition (MSR) reserves space on each disk drive for subsequent use by operating system software. GPT disks do not allow hidden sectors. Software components that formerly used hidden sectors now allocate portions of the MSR for component-specific partitions. For example, converting a basic disk to a dynamic disk causes the MSR on that disk to be reduced in size and a newly created partition holds the dynamic disk database. The MSR has the Partition GUID:

DEFINE_GUID (PARTITION_MSFT_RESERVED_GUID, 0xE3C9E316L, 0x0B5C, 0x4DB8, 0x81, 0x7D, 0xF9, 0x2D, 0xF0, 0x02, 0x15, 0xAE)

Disks that require an MSR

Every GPT disk must contain an MSR. The order of partitions on the disk should be ESP (if any), OEM (if any) and MSR followed by primary data partition(s). It is particularly important that the MSR be created before other primary data partitions.

Creation responsibilities for MSR

The MSR must be created when disk-partitioning information is first written to the drive. If the manufacturer partitions the disk, the manufacturer must create the MSR at the same time. If Windows partitions the disk during setup, Windows creates the MSR.

Why MSR must be created when the disk is first partitioned

After the disk is partitioned, there will be no free space left to create an MSR.

The size of the MSR

When initially created, the size of the MSR depends on the size of the disk drive:

  • On drives less than 16GB in size, the MSR is 32MB.
  • On drives greater than or equal to 16GB, the MSR is 128 MB.

As the MSR is divided into other partitions, it becomes smaller.

Windows GPT ESP implementation

Partitions required by Windows

For UEFI systems, the boot drive must contain an ESP, an MSR, and at least one basic data partition that contains the operating system. Only one ESP should exist on a system even if multiple operating systems are installed on that system. In a mirrored boot configuration there may actually be two drives with an ESP but they are considered to be a redundant copy of the same ESP. Each data drive must contain at least an MSR and one basic data partition.

All basic data partitions on the drive should be contiguous. As noted above, placing an OEM-specific or other unrecognized partition between data partitions imposes limitations on later volume spanning.

Basic data partition

Basic data partitions correspond to primary MBR partitions 0x6 (FAT), 0x7 (NTFS), or 0xB (FAT32). Each basic partition can be mounted using a drive letter or mount point, other volume device object, or both. Each basic data partition is represented in Windows as a volume device object, and optionally as a mount point or a drive letter.

Identifying a basic data partition

It has the following partition type GUID

DEFINE_GUID (PARTITION_BASIC_DATA_GUID, 0xEBD0A0A2L, 0xB9E5, 0x4433, 0x87, 0xC0, 0x68, 0xB6, 0xB7, 0x26, 0x99, 0xC7);

ESP partition visibility to end users

The ESP partition isn't hidden, but also doesn't have an assigned drive letter. It will not appear in Explorer unless a drive letter gets assigned to it, but some tools will be able to list it.

MSR and OEM-specific partitions visibility to end users

Users will not see these partitions exposed in Windows Explorer, nor is any recognized file system exposed to legacy programs such as Context Indexing. The OEM-specific and other unrecognized partitions will be visible only in the Disk Management MMC snap-in since they will not have a recognizable file system.

Partitions mounted by default by Windows

Windows exposes only basic data partitions. Other partitions with FAT file systems may be mounted, but not exposed only programmatically. Only basic data partitions are assigned drive letters or mount points.

The ESP FAT file system is mounted, but not exposed. This allows programs running under Windows to update the contents of the ESP. Assigning a drive letter to the ESP using mountvol /s will allow access to the partition. Access to the ESP requires admin privilege. Although the MSR, and any partitions created from the MSR, could have recognizable file systems, none are exposed.

Any OEM-specific partitions or partitions associated with other operating systems are not recognized by Windows. Unrecognized partitions with recognizable file systems are treated like the ESP. They will be mounted, but not exposed. Unlike MBR disks, there is no practical difference between OEM-specific partitions and other operating system partitions; all are 'unrecognized.'

How the user can see the ESP, OEM, and other unrecognized partitions

The user can use disk management tools such as the Disk Management utility or the diskpart.exe Windows command line. The MSR and any partitions created from the MSR are only visible from the command line.

Dynamic disks

Dynamic disks use two different GPT partitions

  • A data container partition that corresponds to the MBR partition 0x42, with the following GUID:DEFINE_GUID (PARTITION_LDM_DATA_GUID, 0xAF9B60A0L, 0x1431, 0x4F62, 0xBC, 0x68, 0x33, 0x11, 0x71, 0x4A, 0x69, 0xAD);

  • A partition to contain the dynamic configuration database, with the following GUID:DEFINE_GUID(PARTITION_LDM_METADATA_GUID, 0x5808C8AAL, 0x7E8F, 0x42E0, 0x85, 0xD2, 0xE1, 0xE9, 0x04, 0x34, 0xCF, 0xB3);

Volumes are created in the data container and mounted by default. Again, this is exactly the same as the contents of 0x42 MBR partitions.

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Converting a basic disk to dynamic

For a drive to be eligible for conversion to dynamic, all basic data partitions on the drive must be contiguous. If other unrecognized partitions separate basic data partitions, the disk can't be converted. This is one of the reasons that the MSR must be created before any basic data partitions. The first step in conversion is to separate a portion of the MSR to create the configuration database partition. All non-bootable basic partitions are then combined into a single data container partition. Boot partitions are retained as separate data container partitions. This is analogous to conversion of primary partitions.

Windows XP and later versions of Windows differ from Windows 2000 in that basic and extended partitions are preferentially converted to a single 0x42 partition, rather than being retained as multiple distinct 0x42 partitions as on Windows 2000.

A system containing a mix of GPT and MBR dynamic disks

Yes. For more information, see What about mixing and matching GPT and MBR disks on the same system?

Mounting a specific partition

You can access the GPT disk partitions of different types using the tools that are listed in the following table.

Diskpart.efi Disk Partition ToolESP MSR Data
Diskpart.exe Disk Partition ToolESP MSR Data
Diskmgmt.msc Logical Disk ManagerESP Data
Explorer.exe File ExplorerData

By using the Microsoft Platform SDK APIs, you can also develop your own tools to access the GPT disk partitions at their primitive levels.

How GPT disks are managed in Windows

GPT and MBR disks are managed the same way. Disks can be formatted as GPT or MBR by using the Diskpart.exe command prompt utility or by using the Disk Administrator snap-in. Volumes can be created on both GPT and MBR disks, and both kinds of disks can be mixed in the same dynamic disk group.

FTdisk sets

Starting with Windows XP, there is no FTdisk set support on Windows for MBR or GPT disks. The only support for logical volumes is through dynamic disks.

Converted a disk from GPT to MBR, and vice versa

Microsoft offers MBR2GPT.exe which converts disks from MBR to GPT.

File systems supported on GPT disks

NTFS is recommended on all basic data partitions and all dynamic volumes. Windows Setup and the Disk Management snap-in offer only NTFS. To circumvent that, the partition or volume must be formatted explicitly via the Format command-line tool.

Manipulating GPT disks and their contents

Creating a GPT disk

You can create a GPT disk only on an empty, unpartitioned disk (raw disk or empty MBR disk). For more information about creating GPT disks, see Using GPT Drives.

Converting an MBR or GPT disk

You can convert an existing partition format to another format. For more information, see the following TechNet articles:

Do not make a sector-by-sector copy of a GPT disk

The Disk and Partition GUIDs will no longer be unique. This must never happen. You can make a sector-by-sector copy of the contents of ESP or basic data partitions.

Copying a whole GPT disk using the OPK imaging tools

You can copy a whole GPT disk using the OPK imaging tools; however, there are some key caveats. The OEM Preinstallation Kit (OPK) initializes the Disk and Partition GUIDs to zero. On first boot of Windows, the operating system generates unique GUIDs. The OPK only supports generation of ESP, MSR, and basic data partitions.

If an application has recorded any Disk or Partition GUIDs it may break. Any applications, drivers, utilities, or firmware implementations supplied by system manufacturers or application vendors that rely on GUIDs should be capable of handling GUIDs that change from the OPK initialization values to those generated by the operating system.

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The Diskpart.efi MAKE command

The Diskpart.efi MAKE command is a way for OEMs to simplify operating system preinstallation and system recovery. This command can easily be extended to create a 'default' disk configuration for the platform. For example, the system manufacturer could extend the MAKE command to automatically partition the boot drive with an ESP, MSR, an OEM-specific partition, and one basic data partition.

For example, consider a possible disk configuration called BOOT_DISK. In the event of business failure recovery, MAKE BOOT_DISK would allow the customer to completely repartition a boot disk to the original factory defaults.

Detecting a duplicate Disk or Partition GUID

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If Windows detects a duplicate Disk or Partition GUID, Windows will generate new GUIDs for any duplicate Disk GUID, MSR Partition GUID, or MSR basic data GUID upon detection. This is similar to the duplicate MBR signature handling in Windows 2000. Duplicate GUIDs on a dynamic container or database partition cause unpredictable results.