Product Documentation

Disk Image Formats (VHD and VMDK)

Oct 16, 2015

Using the Import wizard, you can import a disk image into a resource pool or into a specific host as a VM.

You might want to import a disk image when only a virtual disk image is available, but there is no OVF metadata associated with it. Situations when this might occur include:
  • The OVF metadata is not readable. However, it is still possible to import the disk image.
  • You have a virtual disk that is not defined in an OVF package.
  • You are moving from a platform that does not let you create an OVF appliance (for example, older platforms or images).
  • You want to import an older VMware appliance that does not have any OVF information.
  • You want to import a standalone VM that does not have any OVF information.

When available, Citrix recommends importing appliance packages that contain OVF metadata and not just importing an individual disk image. The OVF data provides information that the Import wizard needs to recreate a VM from its disk image, including the number of disk images associated with the VM, the processor, storage, and memory requirements and so on. Without this information, it can be much more complex and error-prone trying to recreate the VM.

Note that in a XenServer environment where Role-Based Access Control (RBAC) is implemented, only users with the RBAC role of Pool Admin can import disk images. See RBAC overview for more information about RBAC roles.

Supported disk image formats

The following disk image formats can be imported using the XenCenter Import wizard:
Format Description
Virtual Hard Disk (VHD) VHD is a group of virtual disk image formats specified by Microsoft as part of their Open Specification Promise. Their file extension is .vhd. XenCenter imports and exports the Dynamic VHD format – a thinly provisioned virtual disk image that allocates space only when used.
Virtual Machine Disk (VMDK) VMDK is a group of virtual disk image formats specified by VMware. Their file extension is .vmdk. XenCenter imports stream-optimized and monolithic flat VMDK formats. Stream-optimized VMDK is the format used by OVF packages produced for VMware and Virtual Box hypervisors. Monolithic flat VMDK is a common format of a virtual disk available for download by VMware management clients.

Using Operating System Fixup

XenCenter includes an advanced hypervisor interoperability feature Operating System Fixup which aims to ensure a basic level of interoperability for VMs created on hypervisors other than XenServer. It is necessary to run Operating System Fixup when importing VMs from disk images that were created on other hypervisors to ensure that they boot correctly on XenServer.

To find out more, see About VM Import and Export .