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47 lines
2.4 KiB
XML
47 lines
2.4 KiB
XML
<?xml version="1.0"?>
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<html>
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<body>
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<h1>Architecture</h1>
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<p>Libvirt is a C toolkit to interact with the virtualization capabilities of
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recent versions of Linux (and other OSes), but libvirt won't try to provide
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all possible interfaces for interacting with the virtualization features.</p>
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<p>To avoid ambiguity about the terms used here here are the definitions for
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some of the specific concepts used in libvirt documentation:</p>
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<ul>
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<li>a <strong>node</strong> is a single physical machine</li>
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<li>an <strong>hypervisor</strong> is a layer of software allowing to
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virtualize a node in a set of virtual machines with possibly different
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configurations than the node itself</li>
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<li>a <strong>domain</strong> is an instance of an operating system running
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on a virtualized machine provided by the hypervisor</li>
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</ul>
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<p class="image">
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<img alt="Hypervisor and domains running on a node" src="node.gif"/>
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</p>
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<p>Now we can define the goal of libvirt: to provide the lowest possible
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generic and stable layer to manage domains on a node.</p>
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<p>This implies the following:</p>
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<ul>
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<li>the API should not be targeted to a single virtualization environment
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though Xen is the current default, which also means that some very
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specific capabilities which are not generic enough may not be provided as
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libvirt APIs</li>
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<li>the API should allow to do efficiently and cleanly all the operations
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needed to manage domains on a node</li>
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<li>the API will not try to provide high level multi-nodes management
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features like load balancing, though they could be implemented on top of
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libvirt</li>
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<li>stability of the API is a big concern, libvirt should isolate
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applications from the frequent changes expected at the lower level of the
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virtualization framework</li>
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</ul>
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<p>So libvirt should be a building block for higher level management tools
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and for applications focusing on virtualization of a single node (the only
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exception being domain migration between node capabilities which may need to
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be added at the libvirt level). Where possible libvirt should be extendable
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to be able to provide the same API for remote nodes, however this is not the
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case at the moment, the code currently handle only local node accesses
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(extension for remote access support is being worked on, see <a href="bugs.html">the mailing list</a> discussions about it).</p>
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</body>
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</html>
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