Configure BIOS/MBR-Based Hard Drive Partitions

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 BIOS-based computer.

In this topic:

  • Drive Partition Rules

  • Partition Configurations

  • System and Utility Partitions

  • Related Sample Files

Drive Partition Rules

When you deploy Windows® to a BIOS-based computer, 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.

Windows partition requirements:

  • System partition (with Windows RE tools)

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

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

    To avoid the four-partition limit on BIOS-based systems, we recommend adding the Windows RE tools image onto the system partition.

    The minimum size of this combined partition is 350 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.

  • 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 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 image partition

    When used, this partition includes the Windows recovery image used by push-button reset utilities (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.

Partition Configurations

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

Default Configuration: System and Windows Partitions

The Windows Setup default configuration has a system partition and a Windows partition. This configuration allows BitLocker Drive Encryption to be enabled, and Windows RE to be stored in the hidden system partition. The following diagram shows the default configuration.

You can use this configuration to add system tools such as Windows BitLocker Drive Encryption and Windows Recovery Environment (Windows RE) to your customized Windows installation.

This recommended configuration includes a system partition, a Windows partition, and a recovery image partition. The following diagram shows the recommended configuration.

Add the system partition before you add the Windows partition. Add the partition that contains the recovery image at the end. Copy the Windows RE tools into the System partition, and copy the Windows RE recovery image into the Recovery Image partition. This partition order helps keep the system partition and the Windows RE tools safe during actions such as removing the recovery image partition or changing the size of the Windows 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 set partitions as utility partitions

  • When you are deploying Windows by using Windows Setup, use an answer file to configure your partitions. For the utility partition, set the Microsoft-Windows-Setup\DiskConfiguration\Disk\ModifyPartition\TypeID value to 0x27.

  • When you are deploying Windows by using the DiskPart tool, use the set id=27 command after you create the partition.

To verify that system and utility partitions exist

  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 BIOS-based and MBR-based computer.

Sample: Configure BIOS/MBR-Based Hard Drive Partitions by Using Windows Setup

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

Sample: Configure BIOS/MBR-Based Hard Disk 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 computer.

See Also


Configure More than Four Partitions on a BIOS/MBR-Based Hard Disk
Configure UEFI/GPT-Based Hard Drive Partitions
BitLocker Drive Encryption

Other Resources

Configuring Disk Mirroring