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Created: March 23, 2009.
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Open Virtualization Format (OVF) Version 1.0 Published as a DMTF Standard.


The Distributed Management Task Force (DMTF) has announced publication of Open Virtualization Format Specification Version 1.0.0 as a DMTF Standard. The Open Virtualization Format (OVF) Specification describes an open, secure, portable, efficient and extensible format for the packaging and distribution of software to be run in virtual machines.

The OVF Specification was produced by members of the DMTF System Virtualization, Partitioning, and Clustering Working Group as part of VMAN. DMTF's Virtualization Management Initiative (VMAN) "includes a set of specifications that address the management lifecycle of a virtual environment. VMAN's OVF (Open Virtualization Format) specification provides a standard format for packaging and describing virtual machines and applications for deployment across heterogeneous virtualization platforms. VMAN's profiles standardize many aspects of the operational management of a heterogeneous virtualized environment."

As described in the OVF Technical Note, OVF "is a common packaging format for ISVs to package and securely distribute virtual appliances. A virtual appliance is a pre-built software solution, comprised of one or more VMs that are packaged, maintained, updated and managed as a unit. By creating virtual appliances, software developers can ship preinstalled, pre-configured solutions that enable end-users to literally plug applications into their environments with minimal effort. This enables portability of virtual appliances across multiple virtualization platforms and products... OVF uses XML for capturing metadata about virtual appliance. By packaging virtual appliances in OVF independent software vendors can create a single pre-packaged appliance that can run on customers' virtualization platforms of choice. OVF provides meta-data that can be used to simplify the installation and deployment process for customers. Customers also get greater flexibility by facilitating the mobility of virtual appliances across diverse virtualization platforms. The OVF XML file contains metadata about VMs and includes multiple sections. These sections contain meta-data such as virtual disk, network, resource requirements (e.g., CPU and memory limits), licensing, product, VM startup sequence as well as configuration information about one or more virtual machines. OVF is extensible and enables the OVF package author/creator to include additional metadata..."

The Open Virtualization Format White Paper has been published as a companion document to the Open Virtualization Format Specification. It clarifies, in the Overview:

The rapid adoption of virtual infrastructure has highlighted the need for a standard, portable meta-data model for the distribution of virtual machines to and between virtualization platforms. Packaging an application together with the operating system on which it is certified, into a virtual machine that can be easily transferred from an ISV, through test and development and into production as a pre-configured, pre-packaged unit with no external dependencies, is extremely attractive. Such pre-deployed, ready to run applications packaged as virtual machines (VMs) are called virtual appliances. In order to make this concept practical on a large scale it is important that the industry adopts a vendor-neutral standard for the packaging of such VMs and the meta-data that are required to automatically and securely install, configure, and run the virtual appliance on any virtualization platform.

Virtual appliances are changing the software distribution paradigm because they allow application builders to optimize the software stack for their application and deliver a turnkey software service to the end user. For solution providers, building a virtual appliance is simpler and more cost effective than building a hardware appliance, since the application is pre-packaged with the operating system that it uses, reducing application/OS compatibility testing and certification, and allowing the software to be pre-installed in the OS environment it will run in — by the ISV. For end users, virtual appliances offer an opportunity to dramatically simplify the software management lifecycle through the adoption of a standardized, automated, and efficient set of processes that replace OS and application specific management tasks today.

Whereas current virtual appliances contain a single VM only, modern enterprise applications model service oriented architectures (SOA) with multiple tiers, where each tier contains one or more machines. A single VM model is thus not sufficient to distribute a multi-tier service. In addition, complex applications require install-time customization of networks and other customer specific properties. Furthermore, a virtual appliance is packaged in a run-time format with hard disk images and configuration data suitable for a particular hypervisor. Run-time formats are optimized for execution and not for distribution. For efficient software distribution, a number of additional features become critical, including portability, platform independence, verification, signing, versioning, and licensing terms.

The Open Virtualization Format (OVF) specification is a hypervisor-neutral, efficient, extensible, and open specification for the packaging and distribution of virtual appliances composed of one or more VMs. It aims to facilitate the automated, secure management not only of virtual machines but the appliance as a functional unit. For the OVF format to succeed it must be developed and endorsed by ISVs, virtual appliance vendors, operating system vendors, as well as virtual platform vendors, and must be developed within a standards-based framework..."

OVF Version 1.0: Bibliographic Information

  • Open Virtualization Format Specification. DMTF Document Number: DSP0243. Date: 2009-02-22. Version: 1.0.0. Document Type: Specification. Document Status: DMTF Standard. Document Language: English. 41 pages. Copyright © 2009 Distributed Management Task Force, Inc. (DMTF). Source PDF: Normative ANNEX C presents the OVF XML Schema (XSD).

    Prepared by members of the DMTF System Virtualization, Partitioning, and Clustering Working Group. Contributors: Simon Crosby (XenSource), Ron Doyle (IBM), Mike Gering (IBM), Michael Gionfriddo (Sun Microsystems), Steffen Grarup (VMware - Co-Editor), Steve Hand (Symantec), Mark Hapner (Sun Microsystems), Daniel Hiltgen (VMware), Michael Johanssen (IBM), Lawrence J. Lamers (VMware - Chair), John Leung (Intel Corporation), Fumio Machida (NEC Corporation), Andreas Maier (IBM), Ewan Mellor (XenSource), John Parchem (Microsoft), Shishir Pardikar (XenSource), Stephen J. Schmidt (IBM), René W. Schmidt (VMware -Co-Editor), Andrew Warfield (XenSource), Mark D. Weitzel (IBM), John Wilson (Dell).

  • Open Virtualization Format White Paper. Version 1.0.0. OVF version 1.0.0e. Status: Informational. Publication Date: 2/6/2009. Reference number: DSP2017. 39 pages. Source PDF:

    Abstract: "This white paper describes the Open Virtualization Format (OVF). OVF is a hypervisor-neutral, efficient, extensible, and open specification for the packaging and distribution of virtual appliances composed of one or more virtual computer systems. The target audience of this white paper is anyone who wants to understand OVF and its reason for development. Some familiarity with virtualization and the general concepts of the CIM model is assumed."

Specification Overview

From the Open Virtualization Format Specification Version 1.0

Introduction: "The Open Virtualization Format (OVF) Specification describes an open, secure, portable, efficient and extensible format for the packaging and distribution of software to be run in virtual machines... It is not an explicit goal for OVF to be an efficient execution format. A hypervisor is allowed but not required to run software in virtual machines directly out of the Open Virtualization Format...

The key properties of the format are as follows:

  • Optimized for distribution: OVF supports content verification and integrity checking based on industry-standard public key infrastructure, and it provides a basic scheme for management of software licensing.

  • Optimized for a simple, automated user experience: OVF supports validation of the entire package and each virtual machine or metadata component of the OVF during the installation phases of the virtual machine (VM) lifecycle management process. It also packages with the package relevant user-readable descriptive information that a virtualization platform can use to streamline the installation experience.

  • Supports both single VM and multiple-VM configurations: OVF supports both standard single VM packages and packages containing complex, multi-tier services consisting of multiple interdependent VMs.

  • Portable VM packaging: OVF is virtualization platform neutral, while also enabling platform-specific enhancements to be captured. It supports the full range of virtual hard disk formats used for hypervisors today, and it is extensible, which allow it to accommodate formats that may arise in the future. Virtual machine properties are captured concisely and accurately.

  • Vendor and platform independent: OVF does not rely on the use of a specific host platform, virtualization platform, or guest operating system.

  • Extensible: OVF is immediately useful and extensible. OVF is designed to be extended as the industry moves forward with virtual appliance technology. It also supports and permits the encoding of vendor-specific metadata to support specific vertical markets.

  • Localizable: OVF supports user-visible descriptions in multiple locales, and it supports localization of the interactive processes during installation of an appliance. This capability allows a single packaged appliance to serve multiple market opportunities.

  • Open standard: OVF has arisen from the collaboration of key vendors in the industry, and it is developed in an accepted industry forum as a future standard for portable virtual machines.

From the Open Virtualization Format White Paper

Virtual Appliances: "A virtual appliance is a pre-configured software stack comprising one or more virtual machines. Each virtual machine is an independently installable run-time entity comprising an operating system, applications and other application-specific data, as well as a specification of the virtual hardware that is required by the virtual machine. Many infrastructure applications and even end-user applications that are accessible over a network, such as a DNS server, a bug tracking database, or a complete CRM solution composed of a web, application and database tier, can be delivered as virtual appliances. Delivering complex software systems and services as a pre-configured software stack can dramatically increase robustness and simplify installation. Virtual appliances need not be developed and delivered by third party ISVs — the concept is equally useful and often used within an enterprise in which a virtual machine template for a particular service is assembled, tested, and certified by an IT organization and then packaged for repeated, 'cookie cutter' deployment throughout the enterprise.

Commonly, a software service is implemented as a multi-tier application running in multiple virtual machines and communicating across the network. Services are often composed of other services, which themselves might be multi-tier applications or composed of other services. This is known as service-oriented architecture or SOA. Indeed the SOA-type model naturally fits into a virtual appliance-based infrastructure, since virtual appliances are typified by the use of network facing, XML based management and service interfaces that allow composition of appliances to deliver a complete application.

For example, consider a typical web application that consists of three tiers. A web tier that implements the presentation logic, and application server tier that implements the business logic, and a back-end database tier. A straightforward implementation would divide this into 3 virtual machines, one for each tier. In this way, the application can scale from the fraction of a single physical host to 3 physical hosts. Another approach is to treat each tier as a service in itself. Hence, each tier is a multi-VM service that provides a clustered solution. This can provide far greater scalability than just up to 3 physical hosts. Taking the web-front example, a common scenario is to have many web servers, fewer applications servers, and one or two database servers. Implemented as virtual machines, each tier can scale across as many or as few physical machines as required, and each tier can support multiple instances of service VMs....

From the user's point of view, an OVF is a packaging format for software appliances. Once installed, an OVF adds to the user's infrastructure a self-contained, self-consistent, software solution for achieving a particular goal. For example, an OVF might contain a fully-functional and tested web-server / database / OS combination, such as a LAMP stack (Linux + Apache + MySQL + PHP), or it may contain a virus checker, including its update software, spyware detector, etc.

From a technical point of view, an OVF is a transport mechanism for virtual machine templates. One OVF may contain a single VM, or many VMs (it is left to the software appliance developer to decide which arrangement best suits their application). OVFs must be installed before they can be run; a particular virtualization platform may run the VM from the OVF, but this is not required. If this is done, the OVF itself can no longer be viewed as a 'golden image' version of the appliance, since run-time state for the virtual machine(s) will pervade the OVF. Moreover the digital signature that allows the platform to check the integrity of the OVF will be invalid.

As a transport mechanism, OVF differs from VMware's VMDK Virtual Disk Format and Microsoft's VHD Virtual Hard Disk format or the open source QCOW format. These are run-time VM image formats, operating at the scope of a single VM disk, and though they are frequently used as transport formats today, they are not designed to solve the VM portability problem; they don't help you if you have a VM with multiple disks, or multiple VMs, or need customization of the VM at install time, or if your VM is intended to run on multiple virtualization platforms (even if the virtualization platforms claim support of the particular virtual hard disk format used).

Included within the OVF remit is the concept of the certification and integrity of a packaged software virtual appliance, allowing the platform to determine the provenance of the appliance, and to allow the end-user to make the appropriate trust decisions. The OVF specification has been constructed so that the appliance is responsible for its own configuration and modification. In particular, this means that the virtualization platform does not need to be able to read from the appliance's file systems. This decoupling of platform from appliance means that OVFs may be implemented using any operating system, and installed on any virtualization platform that supports the OVF format. A specific mechanism is provided for appliances to detect the platform on which they are installed, and react to it. This allows platforms to extend this specification in unique ways without breaking compatibility of appliances across the industry..."

From the DMTF Announcement

From the DMTF announcement 2009-03-23: "DMTF Releases OVF 1.0 Standard. OVF Standard Offers Platform Independence in Virtualized Environments. New White Paper Helps Enable Industry Adoption."

The Distributed Management Task Force (DMTF), the industry organization bringing the IT industry together to collaborate on systems management standards development, validation, promotion and adoption, today announced the release of version 1.0 of its Open Virtualization Format (OVF) standard. The updated standard extends DMTF's mission to enable interoperability through the creation of systems management standards for virtualized environments.

"The goal of standards development is to enable Independent Software Vendors (ISVs) to offer improved products that manage a broader range of their customers' preferred technology platforms," said Cameron Haight, Research Vice President with Gartner. "This is because standards, when designed appropriately, not only prevent ISVs from having to create multiple versions of the same product for each possible environment, but they allow vendors to focus their scare development resources upon delivering higher value features."

As part of the DMTF Virtualization Management Initiative (VMAN), OVF simplifies interoperability, security and virtual machine lifecycle management by describing an open, secure, portable, efficient and extensible format for the packaging and distribution of one or more virtual appliances and applications. This enables software developers to ship pre-configured, ready-to-deploy solutions, allowing end-users to distribute applications into their environments with minimal effort. The standard can also serve as a building block for cloud computing.

OVF Version 1.0 Benefits

Key benefits of the OVF standard include:

  • Portable virtual machine (VM) packaging
  • Optimization for secure distribution
  • Simplified installation and deployment
  • Support for both single VM and multi-VM configurations
  • Vendor and platform independent
  • Extensible
  • Localizable

"OVF is the first standard to enable interoperability within virtualized environments, offering customers virtualization platform independence and flexibility," said Winston Bumpus, DMTF president. "The delivery of the 1.0 standard is an indication of DMTF's continued commitment to driving standardization of IT management systems."

DMTF standards on our public web site are available to the industry at no charge. The OVF specification can be downloaded here along with sample demonstrations of the technology from DMTF member companies.

To accompany OVF, DMTF has completed a white paper describing the basic components of the standard and its reason for development. DMTF is committed to promoting the adoption of its management standards. The OVF white paper serves as an educational resource for implementers seeking interoperable solutions for their virtual systems.

About the DMTF VMAN Initiative

The Virtualization Management Initiative (VMAN) from DMTF unleashes the power of virtualization by delivering broadly supported interoperability and portability standards to virtual computing environments. VMAN provides IT managers the freedom to deploy pre-installed, pre-configured solutions across heterogeneous computing networks and to manage those applications through their entire lifecycle. Management software vendors will offer a broad selection of tools that support the industry standard specifications that are a part of VMAN, thus lowering support and training costs for IT managers.

Thanks to the Open Virtualization Format (OVF) standard within VMAN, ISVs can create a single pre-packaged virtual appliance that can run on customers' virtualization platforms of choice. Tools based on the VMAN Profiles enable consistent management and monitoring of these virtual applications across the virtualized platform. These technologies will allow ISVs and platform vendors to focus their development resources on higher value features of their products instead of needing to create different versions of products for each environment...

About the Distributed Management Task Force

DMTF enables more effective management of millions of IT systems worldwide by bringing the IT industry together to collaborate on the development, validation and promotion of systems management standards. The group spans the industry with 160 member companies and organizations, and more than 4,000 active participants crossing 43 countries. The DMTF board of directors is led by 16 innovative, industry-leading technology companies. They include Advanced Micro Devices (AMD); Broadcom Corporation; CA; Dell; EMC; Fujitsu; HP; Hitachi, Ltd.; IBM; Intel Corporation; Microsoft Corporation; Novell; Oracle; Sun Microsystems, Inc.; Symantec and VMware. With this deep and broad reach, DMTF creates standards that enable interoperable IT management. DMTF management standards are critical to enabling management interoperability among multi-vendor systems, tools and solutions within the enterprise.

The DMTF's top-level committees, the Alliance Committee, Interoperability Committee, Marketing Committee, and Technical Committee, oversee the operations of the DMTF's subcommittees and working groups. Committees can form subcommittees, which focus on issues in specific areas of the committee's charter. Under subcommittees are the working groups. All groups are comprised of DMTF members with specific areas of expertise helping to develop the various standards, specifications, and other documents in support of managing enterprise and Internet environments.

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