| 1 | <?xml version='1.0' encoding='UTF-8'?>
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| 2 | <!DOCTYPE topic PUBLIC "-//OASIS//DTD DITA Topic//EN" "topic.dtd">
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| 3 | <topic xml:lang="en-us" id="ovf-about">
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| 4 | <title>About the OVF Format</title>
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| 5 |
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| 6 | <body>
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| 7 | <p>
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| 8 | OVF is a cross-platform standard supported by many
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| 9 | virtualization products which enables the creation of ready-made
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| 10 | virtual machines that can then be imported into a hypervisor
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| 11 | such as <ph conkeyref="vbox-conkeyref-phrases/product-name"/>. <ph conkeyref="vbox-conkeyref-phrases/product-name"/> makes OVF import and
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| 12 | export easy to do, using <ph conkeyref="vbox-conkeyref-phrases/vbox-mgr"/> or the command-line
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| 13 | interface.
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| 14 | </p>
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| 15 | <p>
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| 16 | Using OVF enables packaging of <i>virtual
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| 17 | appliances</i>. These are disk images, together with
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| 18 | configuration settings that can be distributed easily. This way
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| 19 | one can offer complete ready-to-use software packages, including
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| 20 | OSes with applications, that need no configuration or
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| 21 | installation except for importing into <ph conkeyref="vbox-conkeyref-phrases/product-name"/>.
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| 22 | </p>
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| 23 | <note>
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| 24 | <p>
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| 25 | The OVF standard is complex, and support in <ph conkeyref="vbox-conkeyref-phrases/product-name"/> is
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| 26 | an ongoing process. In particular, no guarantee is made that
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| 27 | <ph conkeyref="vbox-conkeyref-phrases/product-name"/> supports all appliances created by other
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| 28 | virtualization software. For a list of known limitations, see
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| 29 | <xref href="KnownIssues.dita">Known Limitations</xref>.
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| 30 | </p>
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| 31 | </note>
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| 32 | <p>
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| 33 | Appliances in OVF format can appear in the following variants:
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| 34 | </p>
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| 35 | <ul>
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| 36 | <li>
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| 37 | <p>
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| 38 | They can come in several files, as one or several disk
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| 39 | images, typically in the widely-used VMDK format. See
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| 40 | <xref href="vdidetails.dita"/>. They also include a textual
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| 41 | description file in an XML dialect with an
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| 42 | <filepath>.ovf</filepath> extension. These files must then
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| 43 | reside in the same directory for <ph conkeyref="vbox-conkeyref-phrases/product-name"/> to be able
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| 44 | to import them.
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| 45 | </p>
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| 46 | </li>
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| 47 | <li>
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| 48 | <p>
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| 49 | Alternatively, the above files can be packed together into a
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| 50 | single archive file, typically with an
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| 51 | <filepath>.ova</filepath> extension. Such archive files use
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| 52 | a variant of the TAR archive format and can therefore be
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| 53 | unpacked outside of <ph conkeyref="vbox-conkeyref-phrases/product-name"/> with any utility that can
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| 54 | unpack standard TAR files.
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| 55 | </p>
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| 56 | </li>
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| 57 | </ul>
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| 58 | <note>
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| 59 | <p>
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| 60 | OVF cannot describe snapshots that were taken for a virtual
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| 61 | machine. As a result, when you export a virtual machine that
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| 62 | has snapshots, only the current state of the machine will be
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| 63 | exported. The disk images in the export will have a
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| 64 | <i>flattened</i> state identical to the current
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| 65 | state of the virtual machine.
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| 66 | </p>
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| 67 | </note>
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| 68 | </body>
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| 69 |
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| 70 | </topic>
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