qcow2-slice.xml

<disk device='disk' name='vda'>
  <driver type='qcow2'/>
  <source file='/var/lib/libvirt/images/i.qcow2'>
    <slices>
      <slice type='storage' offset='1234' size='5768'/>
    </slices>
    <privateData>
      <nodenames>
        <nodename type='storage' name='0123456789ABCDEF0123456789ABCDE'/>
        <nodename type='format' name='0123456789ABCDEF0123456789ABCDE'/>
      </nodenames>
    </privateData>
  </source>
</disk>