Citrix Provisioning

Converting BIOS vDisks to UEFI

This article explains how to convert the BIOS vDisks to UEFI. This conversion is important because BIOS support is removed in Citrix Provisioning version 2311 and onwards.

There are two approaches to convert an existing vDisk from BIOS format to UEFI:


In both the approaches, ensure that:

  • There is sufficient free space
  • The disk is defragmented before starting. You can do this step either after reverse imaging or before merging the vDisk to a single version.

Image Portability Service can be used to automate the conversion to UEFI. For more information, see Convert to UEFI.

Convert the vDisk directly

Do the following steps to convert the vDisk directly:

  1. Ensure that the disk is defragmented and merged down to a single base version.
  2. Copy the .VHD(X) file to a new file in the store.
  3. Run disk management in windows and attach the VHD.
  4. Run diskpart to determine the disk number of the mounted disk.

    Run diskpart

  5. Run the following command to convert the mounted vdisk file to UEFI (GPT).

    mbr2gpt /convert /disk:3 /allowFullOS
  6. Unmount the VHD file and import into the Citrix Provisioning store.

Convert the vDisk using reverse imaging

Do the following steps to Convert the vDisk using reverse imaging:

  1. Reverse image to a master VM setup as BIOS with a local disk that is large enough.
  2. Reboot the VM from the local disk (change the boot order) and log on as an administrator.
  3. Run diskpart to confirm the disk number. The number must be zero.
  4. Run the following command to convert the disk to UEFI (GPT).

    mbr2gpt /convert /disk:0 /allowFullOS
  5. Shut down the VM.
  6. Update the hypervisor configuration for the VM to use UEFI. For example:

    • With VMware as a hypervisor, go to the VM Edit Settings and from the VM Options tab> Boot Options section, select the firmware type as EFI.

    Set boot option as EFI in VMware

    • With XenServer as the hypervisor:

      1. Determine the UUID of the original VM. You can get the UUID from XenCenter or use the xe vm-list name-label="VM NAME" as shown:

        [root@xenserver01 ~]# xe vm-list name-label="Windows 10 BIOS"
        uuid ( RO)           : e98a0a89-2fb9-886b-a843-b8a08642afa4
        name-label ( RW): Windows 10 BIOS
        power-state ( RO): halted
      2. Set the VM to use UEFI boot with xe vm-param-set uuid=UUID HVM-boot-params:firmware=uefi as shown:

        [root@xenserver01 ~]# xe vm-param-set uuid=e98a0a89-2fb9-886b-a843-b8a08642afa4 HVM-boot-params:firmware=uefi
  7. Boot the VM and run the Imaging Wizard to create a new vDisk for the converted disk.
Converting BIOS vDisks to UEFI