XenCenter

Open Virtualization Format (OVF and OVA)

August 5, 2025

Contributed by:

OVF is an open standard, specified by the Distributed Management Task Force (DMTF), for packaging and distributing a virtual appliance consisting of one or more virtual machines (VMs).

An OVF Package contains metadata and file elements that describe VMs, plus additional information important to the deployment and operation of the applications in the OVF package. Its file name extension is .ovf.

An Open Virtual Appliance (OVA) is an OVF Package in a single file archive with the .ova extension.

In XenServer environments where Role-Based Access Control (RBAC) is implemented, only users with the RBAC role of Pool Admin or Pool Operator can import OVF and OVA packages. To export OVF and OVA packages, you must have the Pool Admin, Pool Operator, VM Power Admin, or VM Admin role. For more information about RBAC roles, see RBAC overview.

What’s in an OVF package?

An OVF Package always includes a descriptor file (*.ovf) and might also include several other files.

File type	Description
Descriptor	The descriptor specifies the virtual hardware requirements of the service. This descriptor can also include information such as virtual disks descriptions, the service itself, guest OSes, a EULA, instructions to start and stop appliance VMs, and instructions to install the service. The descriptor file name extension is `.ovf`.
Manifest	The manifest is an SHA-1 digest of every file in the package, allowing the package contents to be verified by detecting any corruption. The manifest file name extension is `.mf`.
Signature	The signature is the digest of the manifest signed with the public key from the X.509 certificate included in the package. It allows the package author to be verified. The signature file name extension is `.cert`.
Virtual disks	OVF does not specify a disk image format. An OVF package includes files comprising virtual disks in the format defined by the virtualization product that exported the virtual disks. XenServer produces OVF packages with disk images in Dynamic VHD format; VMware products and Virtual Box produce OVF packages with virtual disks in Stream-Optimized VMDK format.

An OVA package is a single archive file, in the Tape Archive (tar) format, containing the files that comprise an OVF Package.

Which format do I use?

OVF packages contain a series of uncompressed files that make it easier to access individual disk images in the file. OVA packages are just one large file. While you can compress this file, it doesn’t have the flexibility of a series of files like OVF.

OVA is better for specific applications where it is beneficial to have a single file, making the package easier to handle, such as creating packages for Web downloads. Exporting and importing OVA packages takes longer than OVF.

You cannot use OVA/OVF to export virtual machines with an attached vTPM.

(Windows VMs only) Installing XenServer VM Tools for Windows

If you also have the Conversion Manager virtual appliance version 8.5.0 or later running in your pool, you can choose to install XenServer VM Tools for Windows as part of an import. If you choose not to install XenServer VM Tools for Windows as part of the import process, ensure that you install them manually later for the VM to be fully supported. For more information, see Install XenServer VM Tools.

(Linux VMs only) Using Operating System Fixup

XenCenter includes an advanced hypervisor interoperability feature Operating System Fixup. This feature aims to ensure a basic level of interoperability for Linux VMs created on hypervisors other than XenServer. If you select a Linux template when importing a disk image that was created on another hypervisor, you can instead choose to run Operating System Fixup as part of the import.

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

More information about OVF

For more information about OVF, see the following documents on the DMTF website:

Open Virtualization Format Specification

XenServer 8.4

Import and export VMs

The official version of this content is in English. Some of the Cloud Software Group documentation content is machine translated for your convenience only. Cloud Software Group has no control over machine-translated content, which may contain errors, inaccuracies or unsuitable language. No warranty of any kind, either expressed or implied, is made as to the accuracy, reliability, suitability, or correctness of any translations made from the English original into any other language, or that your Cloud Software Group product or service conforms to any machine translated content, and any warranty provided under the applicable end user license agreement or terms of service, or any other agreement with Cloud Software Group, that the product or service conforms with any documentation shall not apply to the extent that such documentation has been machine translated. Cloud Software Group will not be held responsible for any damage or issues that may arise from using machine-translated content.

Was this helpful

Open Virtualization Format (OVF and OVA)

August 5, 2025

Contributed by:

Open Virtualization Format (OVF and OVA)

What’s in an OVF package?

Which format do I use?

(Windows VMs only) Installing XenServer VM Tools for Windows

(Linux VMs only) Using Operating System Fixup

More information about OVF

Related documentation

XenServer 8.4

In this article