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Configure UEFI/GPT-Based Hard Drive Partitions

Updated: July 25, 2014

Applies To: Windows 8, Windows 8.1, Windows Server 2008 R2, Windows Server 2012, Windows Server 2012 R2

This topic describes how to configure hard drive partitions including hard disk drives (HDDs), solid-state drives (SSDs), and other drives, for a Unified Extensible Firmware Interface (UEFI)–based PC.

In this topic:

When you deploy Windows® to a UEFI-based PC, 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.

Windows partition requirements:

  • Windows RE Tools partition

    This partition must be at least 300 MB.

    This partition must allocate space for the Windows RE tools image (winre.wim, typically between 250-300MB, depending on base language and customizations added), plus enough free space so that the partition can be captured by backup utilities:

    • If the partition is less than 500 MB, it must have at least 50 MB of free space.

    • If the partition is 500 MB or larger, it must have at least 320 MB of free space.

    • If the partition is larger than 1 GB, we recommend that it should have at least 1 GB free.

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

    • The Windows RE tools should be in a separate partition than the Windows partition to support automatic failover and to support booting Windows BitLocker Drive Encryption-encrypted partitions.

  • System Partition

    The PC should contain one system partition. On Extensible Firmware Interface (EFI) and UEFI systems, this is also known as the EFI System Partition, or the ESP. This partition is usually stored on the primary hard drive. The PC 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.

    noteNote
    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)

    The size of an MSR is 128 MB.

    Add an MSR to each drive for drive 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 must be located before the Windows, data, and recovery image partitions. This allows end users to perform actions such as resizing the Windows partition or reclaiming the recovery image partition without affecting system utilities.

  • Windows partition and other data partitions

    • This partition must have at least 20 gigabytes (GB) of drive space for 64-bit versions, or 16 GB for 32-bit versions.

    • This partition must be formatted using the NTFS file format.

    • This partition must have enough 10 GB of free space after the user has completed the Out Of Box Experience (OOBE).

    • To use the Refresh your PC functionality of push-button reset, the partition may need additional free space. To calculate the amount of space needed, use the formula:

      Image_size x 1.1 + Buffer:

      • Image_size: This is the estimated size of the image after it has been applied from the WIM image file. Use the command:

        Dism /Get-WimInfo /WimFile:C:\test\offline\install.wim
        
        If your WIM image file contains multiple images, use the size information reported for the image configured to be used by push-button reset.

      • Buffer:

        x64: 1.2 GB

        x86: 1.1 GB

        ARM: 1.0 GB

    Each primary partition can have a maximum of 18 exabytes (~18.8 million terabytes) of space.

  • Recovery image partition

    When used, this partition includes the Windows recovery image (install.wim).

    The size of this partition must include space for the Windows recovery image (at least 2 GB), plus enough free space so that the partition can be captured by backup utilities:

    • It must have at least 320 MB of free space.

    • We recommend that it should have at least 1 GB free.

    We recommend that you place this partition after all other partitions. This allows end users to reclaim the space used by the recovery image partition without affecting other system utilities.

For more information about GPT drive and hard drive partitions, see The Windows and GPT FAQ.

This section describes the default partition configuration and the recommended partition configuration.

The Windows Setup default configuration contains a Windows Recovery Environment (Windows RE) Tools partition, a system partition, an MSR, and a Windows partition. The following diagram shows this configuration. This configuration allows BitLocker Drive Encryption to be enabled, and Windows RE to be stored in the hidden system partition.

Diagram of default EFI partitions

By using this configuration, you can add system tools such as Windows BitLocker Drive Encryption and Windows RE to your customized Windows installation.

The recommended configuration includes a Windows RE Tools partition, a system partition, an MSR, a Windows partition, and a recovery image partition. The following diagram shows this configuration.

Diagram of EFI partitions with recovery

Add the Windows RE Tools partition and system partition before you add the Windows partition. Add the partition that contains the recovery image at the end. This partition order helps keep the system and the Windows RE Tools partition safe during actions such as removing the recovery image partition or changing the size of the Windows partition.

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

You can help protect end users from accidentally modifying other partitions in the same way by identifying them as utility partitions.

  • When you are deploying Windows by using the DiskPart tool, 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.

  1. Click Start, right-click Computer, 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.

The following files contain XML samples that demonstrate how to set up partitions on a UEFI-based PC.

 

Sample: Configure UEFI/GPT-Based Hard Drive Partitions by Using Windows Setup

Demonstrates how to add answer-file settings to automatically configure hard drive partitions during Windows installation.

Sample: Configure UEFI/GPT-Based Hard Drive Partitions by Using Windows PE and DiskPart

Demonstrates how to configure partitions by using a DiskPart script to prepare to deploy a Windows image to a new PC.

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