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How to verify that the Windows partition is active

Applies to: ✔️ Windows VMs

This article shows how to verify that the Windows partition is active.

Verify that the Windows partition is active

Note

This mitigation applies only for Generation 1 VMs. Generation 2 VMs (using UEFI) don't use an active partition.

  1. Attach the system disk to a recovery VM.

  2. Start a Remote Desktop connection to the recovery VM.

  3. Open Computer management > Disk management. Make sure that the disk is flagged as Online in the Disk Management console. Note the drive letter that is assigned to the attached system disk.

    Screenshot that shows the disk attached to the recovery VM.

  4. Identify the Boot partition and Windows partition. If there's only one partition on the OS disk, this partition is both Boot partition and Windows partition.

    If the OS disk contains more than one partition, you can identify the partitions by viewing the folders in them:

    • The Windows partition contains a folder that is named Windows, and this partition is larger than the others.

    • The Boot partition contains a folder that is named Boot. This folder is hidden by default. To see the folder, you must display the hidden files and folders and disable the Hide protected operating system files (Recommended) option. The boot partition is typically 300 MB~500 MB.

  5. Run the following command as an administrator to create a boot record:

    bcdboot <Windows partition>:\Windows /S <windows partition>:

  6. Use the DISKPART tool to check whether the Windows partition is active:

    1. Open an elevated command prompt and open the DISKPART tool.

      diskpart

    2. List the disks on the system and look for added disks and proceed to select the new disk. In this example, the new disk is Disk 1.

      list disk
sel disk 1

      The diskpart window shows outputs of list disk and sel disk 1 commands. Disk 0 and Disk 1 are displayed in the table. Disk 1 is the selected disk.

    3. List all the partitions on that disk and then proceed to select the partition you want to check. Usually System Managed partitions are smaller and around 350 MB in size. In the following image, this partition is Partition 1.

      list partition
sel partition 1

      Screenshot that shows the 'Partition 1' is the selected partition.

    4. Check the status of the partition. In our example, Partition 1 is not active.

      detail partition

      The diskpart window with output of the detail partition command where Partition 1 is not active.

      If the partition isn't active, change the Active flag and then recheck the change was done properly.

      active
detail partition

      The diskpart window with output of the detail partition command where Partition 1 is active.

    5. Exit the DISKPART tool.

      exit

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