UEFI/GPT-based hard drive partitions

Create custom partition layouts for your hard disk drives (HDDs), solid-state drives (SSDs), and other drives when deploying Windows to Unified Extensible Firmware Interface (UEFI)–based devices.

If you use a custom partition layout on WindowsВ 10 for desktop editions (Home, Pro, Enterprise, and Education), update the push-button recovery script so the recovery tools can recreate the custom partition layout when needed.

Partition Requirements

When you deploy Windows to a UEFI-based device, you must format the hard drive that includes the Windows partition by using a GUID partition table (GPT) file system. Additional drives may use either the GPT or the master boot record (MBR) file format.

A GPT drive may have up to 128 partitions.

Each partition can have a maximum of 18 exabytes (

18.8 million terabytes) of space.

System partition

The device must contain a system partition. On GPT drives, this is known as the EFI System Partition, or the ESP. This partition is usually stored on the primary hard drive. The device boots to this partition.

The minimum size of this partition is 100 MB, and must be formatted using the FAT32 file format.

This partition is managed by the operating system, and should not contain any other files, including Windows RE tools.

For Advanced Format 4K Native drives (4-KB-per-sector) drives, the minimum size is 260 MB, due to a limitation of the FAT32 file format. The minimum partition size of FAT32 drives is calculated as sector size (4KB) x 65527 = 256 MB.

Advanced Format 512e drives are not affected by this limitation, because their emulated sector size is 512 bytes. 512 bytes x 65527 = 32 MB, which is less than the 100 MB minimum size for this partition.

Microsoft reserved partition (MSR)

In WindowsВ 10, the size of the MSR is 16 MB.

Add an MSR to each GPT drive to help with partition management. The MSR is a reserved partition that does not receive a partition ID. It cannot store user data.

Other utility partitions

Any other utility partitions not managed by Windows must be located before the Windows, data, and recovery image partitions. This allows end users to perform actions such as resizing the Windows partition without affecting system utilities.

Protect end users from accidentally modifying utility partitions by identifying them using a GPT attribute. This prevents these partitions from appearing in File Explorer.

To set partitions as utility partitions

• When you’re deploying Windows by using DiskPart, use the attributes volume set GPT_ATTRIBUTE_PLATFORM_REQUIRED command after you create the partition to identify the partition as a utility partition. For more information, see the MSDN topic: PARTITION_INFORMATION_GPT structure.

To verify that system and utility partitions exist

1. Click Start, right-click This PC, and then click Manage. The Computer Management window opens.
2. Click Disk Management. The list of available drives and partitions appears.
3. In the list of drives and partitions, confirm that the system and utility partitions are present and are not assigned a drive letter.

Windows partition

• The partition must have at least 20 gigabytes (GB) of drive space for 64-bit versions, or 16 GB for 32-bit versions.
• The Windows partition must be formatted using the NTFS file format.
• The Windows partition must have 16 GB of free space after the user has completed the Out Of Box Experience (OOBE) and Automatic Maintenance has completed.

Recovery tools partition

This partition must be at least 300 MB.

The Windows Recovery Environment (Windows RE) tools require additional free space:

• A minimum of 52 MB is required but 250 MB is recommended, to accomodate future updates, especially with custom partition layouts.

When calculating free space, note:

• The recovery image, winre.wim, is typically between 250-300MB, depending on what drivers, languages, and customizations you add.
• The file system itself can take up additional space. For example, NTFS may reserve 5-15MB or more on a 750MB partition.

This partition must use the Type ID: DE94BBA4-06D1-4D40-A16A-BFD50179D6AC.

The recovery tools should be in a separate partition than the Windows partition to support automatic failover and to support booting partitions encrypted with WindowsВ BitLocker Drive Encryption.

We recommend that you place this partition immediately after the Windows partition. This allows Windows to modify and recreate the partition later if future updates require a larger recovery image.

Data partitions

The recommended partition layout for WindowsВ 10 does not include data partitions. However, if data partitions are required, they should be placed after the Windows RE partition. This allows future updates to Windows RE to grow the Windows RE partition by shrinking the Windows partition.

This layout makes it more difficult for end users to remove the data partition and merge the space with the Windows partition. To do so, the Windows RE partition must be moved to the end of the unused space reclaimed from the data partition, so that the Windows partition can be extended.

WindowsВ 10 does not include functionality or utility to facilitate this process. However, manufacturers can develop and provide such a utility if PCs are shipped with data partitions.

Partition layout

The default partition layout for UEFI-based PCs is: a system partition, an MSR, a Windows partition, and a recovery tools partition.

This layout lets you use WindowsВ BitLocker Drive Encryption through both Windows and through the Windows Recovery Environment.

Sample files: configure drive partitions by using WindowsВ PE and DiskPart scripts

For image-based deployment, boot the PC to Windows PE, and then use the DiskPart tool to create the partition structures on your destination PCs.

In these DiskPart examples, the partitions are assigned the letters: System=S, Windows=W, and Recovery=R. The MSR partition does not receive a drive letter.

Change the Windows drive letter to a letter that’s near the end of the alphabet, such as W, to avoid drive letter conflicts. Do not use X, because this drive letter is reserved for Windows PE. After the device reboots, the Windows partition is assigned the letter C, and the other partitions don’t receive drive letters.

If you reboot, WindowsВ PE reassigns disk letters alphabetically, starting with the letter C, without regard to the configuration in Windows Setup. This configuration can change based on the presence of different drives, such as USB flash drives.

The following steps describe how to partition your hard drives and prepare to apply images. You can use the code in the sections that follow to complete these steps.

To partition hard drives and prepare to apply images

Copy and save the CreatePartitions-UEFI.txt file to a USB flash drive.

Use WindowsВ PE to boot the destination PC.

Clean and partition the drive. In this example, F is the letter of the USB flash drive.

1. If you use a custom partition layout on WindowsВ 10 for desktop editions, update the push-button recovery script so the recovery tools can recreate the custom partition layout when needed.

To avoid bare metal recovery boot issues due to partition size, manufacturers should allow the bare metal recovery feature’s auto generation script to create the partition used for the recovery WIM. If manufacturer’s want to use a custom DISKPART script to create partitions, the recommended minimum partition size is 990MB with a minimum of 250MB of free space.

Next steps

Use a deployment script to apply the Windows images on the newly created partitions. For more information, see Capture and Apply Windows, System, and Recovery Partitions.

Create and format a hard disk partition

To create a partition or volume (the two terms are often used interchangeably) on a hard disk, you must be logged in as an administrator, and there must be either unallocated disk space or free space within an extended partition on the hard disk.

If there is no unallocated disk space, you can create some by shrinking an existing partition, deleting a partition, or by using a third-party partitioning program.

Open Computer Management by selecting the Start button. The select Control Panel > System and Security > Administrative Tools, and then double-click Computer Management.

In the left pane, under Storage, select Disk Management.

Right-click an unallocated region on your hard disk, and then select New Simple Volume.

In the New Simple Volume Wizard, select Next.

Enter the size of the volume you want to create in megabytes (MB) or accept the maximum default size, and then select Next.

Accept the default drive letter or choose a different drive letter to identify the partition, and then select Next.

In the Format Partition dialog box, do one of the following:

If you don’t want to format the volume right now, select Do not format this volume, and then select Next.

To format the volume with the default settings, select Next.

Review your choices, and then select Finish.

Note: When you create new partitions on a basic disk, the first three will be formatted as primary partitions. Beginning with the fourth, each one will be configured as a logical drive within an extended partition.

BIOS/MBR-based hard drive partitions

Create custom partition layouts for your hard disk drives (HDDs), solid-state drives (SSDs), and other drives when deploying Windows to BIOS–based devices.

NoteВ В If you use a custom partition layout on WindowsВ 10 for desktop editions (Home, Pro, Enterprise, and Education), update the push-button recovery script so the recovery tools can recreate the custom partition layout when needed.

Partition Requirements

When you deploy Windows to a BIOS-based device, you must format hard drives by using an MBR file system. Windows does not support the GUID partition table (GPT) file system on BIOS-based computers.

An MBR drive can have up to four standard partitions. Typically, these standard partitions are designated as primary partitions. For information about how to create additional partitions beyond this limit, see Configure More than Four Partitions on a BIOS/MBR-Based Hard Disk.

System partition

Each bootable drive must contain a system partition. The system partition must be configured as the active partition.

The minimum size of this partition is 100 MB.

Windows partition

• This partition must have at least 20 gigabytes (GB) of drive space for 64-bit versions, or 16 GB for 32-bit versions.
• The Windows partition must be formatted using the NTFS file format.
• The Windows partition must have 16 GB of free space after the user has completed the Out Of Box Experience (OOBE) and Automatic Maintenance has completed.
• This partition can have a maximum of 2 terabytes (TB) of space. Software tools to extend the visible partition space beyond 2 TB are not supported on BIOS because they can interfere with software solutions for application compatibility and recovery.

Recovery tools partition

Create a separate recovery partition to support automatic failover and to support booting WindowsВ BitLocker Drive Encryption-encrypted partitions.

We recommend that you place this partition in a separate partition, immediately after the Windows partition. This allows Windows to modify and recreate the partition later if future updates require a larger recovery image.

The Windows Recovery Environment (Windows RE) tools require additional free space:

• A minimum of 52 MB is required but 250 MB is recommended, to accomodate future updates, especially with custom partition layouts.

When calculating free space, note:

• The recovery image, winre.wim, is typically between 250-300MB, depending on what drivers, languages, and customizations you add.
• The file system itself can take up additional space. For example, NTFS may reserve 5-15MB or more on a 750MB partition.

Data partitions

The recommended partition layout for WindowsВ 10 does not include utility or data partitions.

However, if utility or data partitions are required, they should be placed either before the Windows partition or after the Windows RE partition. By keeping the Windows and recovery partitions together, then when future updates of Windows RE area available, Windows will be able to grow the Windows RE partition by shrinking the Windows partition.

This layout makes it more difficult for end users to remove the data partition and merge the space with the Windows partition. For example, the Windows RE partition may need to be moved to the end of the unused space reclaimed from the data partition, so that the Windows partition can be extended. WindowsВ 10 does not include functionality or utility to facilitate this process. However, manufacturers can develop and provide such a utility if PCs are shipped with data partitions.

Each partition can have a maximum of 2 terabytes (TB) of space.

If you’re going to be adding more than four total partitions to the disk, see Configure More than Four Partitions on a BIOS/MBR-Based Hard Disk for more info.

Partition layout

If you install Windows using a bootable USB key made by Windows Imaging and Configuration Designer (ICD), it creates the following layout by default: a system partition, a Windows partition, and a recovery tools partition.

System and utility partitions

By default, system partitions do not appear in File Explorer. This helps protect end users from accidentally modifying a partition.

To keep system and utility partitions from being reset, use type 0x27. Do not use any of the following types: 0x7, 0x0c, 0x0b, 0x0e, 0x06, and 0x42.

To set partitions as utility partitions

1. When you are deploying Windows by using Windows ICD, the partition type will be set automatically.
2. When you are deploying Windows by using the DiskPart tool, use the set command after you create the partition.

To verify that system and utility partitions exist

1. Click Start, right-click This PC, and then click Manage. The Computer Management window opens.
2. Click Disk Management. The list of available drives and partitions appears.
3. In the list of drives and partitions, confirm that the system and utility partitions are present and are not assigned a drive letter.

Sample files: configuring disk layout by using WindowsВ PE and DiskPart scripts

For image-based deployment, boot the PC to Windows PE, and then use the DiskPart tool to create the partition structures on your destination PCs.

NoteВ В In these DiskPart examples, the partitions are assigned the letters: System=S, Windows=W, and Recovery=R.

Change the Windows drive letter to a letter that’s near the end of the alphabet, such as W, to avoid drive letter conflicts. Do not use X, because this drive letter is reserved for Windows PE. After the device reboots, the Windows partition is assigned the letter C, and the other partitions don’t receive drive letters.

If you reboot, WindowsВ PE reassigns disk letters alphabetically, starting with the letter C, without regard to the configuration in Windows Setup. This configuration can change based on the presence of different drives, such as USB flash drives.

The following steps describe how to partition your hard drives and prepare to apply images. You can use the code in the sections that follow to complete these steps.

To partition hard drives and prepare to apply images

Save the following code as a text file (CreatePartitions-BIOS.txt) on a USB flash drive.

Use WindowsВ PE to boot the destination computer.

Clean and partition the drive. In this example, F is the letter of the USB flash drive.

If you use a custom partition layout on WindowsВ 10 for desktop editions, update the push-button recovery script so the recovery tools can recreate the custom partition layout when needed.

Important To avoid bare metal recovery boot issues due to partition size, it is recommended that manufacturers allow the bare metal recovery feature’s auto generation script to create the partition used for the recovery WIM. If manufacturer’s wish to use a custom DISKPART script for partition creation, the recommended minimum partition size is 990MB and a minimum of 250MB of free space.

Next steps

Use a deployment script to apply the Windows images on the newly created partitions. For more information, see Capture and Apply Windows, System, and Recovery Partitions.