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<topic xml:lang="en-us" id="ovf-about">
  <title>About the OVF Format</title>
  
  <body>
    <p>OVF is a cross-platform standard supported by many virtualization products which enables the creation of
      ready-made virtual machines that can then be imported into a hypervisor such as <ph
        conkeyref="vbox-conkeyref-phrases/product-name"/>. <ph conkeyref="vbox-conkeyref-phrases/product-name"/> makes
      OVF import and export easy to do, using <ph conkeyref="vbox-conkeyref-phrases/vbox-mgr"/> or the command-line
      interface. </p>
    <p>Using OVF enables packaging of <i>virtual appliances</i>. These are disk images, together with configuration
      settings that can be distributed easily. This way one can offer complete ready-to-use software packages, including
      OSes with applications, that need no configuration or installation except for importing into <ph
        conkeyref="vbox-conkeyref-phrases/product-name"/>. </p>
    <note>
      <p>The OVF standard is complex, and support in <ph conkeyref="vbox-conkeyref-phrases/product-name"/> is an ongoing process. No guarantee is made that <ph conkeyref="vbox-conkeyref-phrases/product-name"/> supports all appliances created by other virtualization software. In particular, the following limitations exist:</p>
      <p>
        <ul>
          <li>
            <p>OVF localization, with multiple languages in a single OVF file, is not yet supported.</p>
          </li>
          <li>
            <p>Some OVF sections like StartupSection, DeploymentOptionSection, and InstallSection are ignored.</p>
          </li>
          <li>
            <p>OVF environment documents, including their property sections are not yet supported.</p>
          </li>
          <li>
            <p>Remote files using HTTP or other mechanisms are not yet supported.</p>
          </li>
        </ul>
      </p>
    </note>
    <p>Appliances in OVF format can appear in the following variants: </p>
    <ul>
      <li>
        <p>They can come in several files, as one or several disk images, typically in the widely-used VMDK format. See
            <xref href="vdidetails.dita"/>. They also include a textual description file in an XML dialect with an
            <filepath>.ovf</filepath> extension. These files must then reside in the same directory for <ph
            conkeyref="vbox-conkeyref-phrases/product-name"/> to be able to import them. </p>
      </li>
      <li>
        <p>Alternatively, the above files can be packed together into a single archive file, typically with an
            <filepath>.ova</filepath> extension. Such archive files use a variant of the TAR archive format and can
          therefore be unpacked outside of <ph conkeyref="vbox-conkeyref-phrases/product-name"/> with any utility that
          can unpack standard TAR files. </p>
      </li>
    </ul>
    <note>
      <p>OVF cannot describe snapshots that were taken for a virtual machine. As a result, when you export a virtual
        machine that has snapshots, only the current state of the machine will be exported. The disk images in the
        export will have a <i>flattened</i> state identical to the current state of the virtual machine. </p>
    </note>
  </body>
  
</topic>
