<disk type='network' device='disk'>
      <driver name='qemu' type='raw' cache='none' io='native' discard='unmap'/>
      <auth username='nebula-public'>
        <secret type='ceph' uuid='81058c7f-4dcd-4b57-bcbe-a9b460df3f09'/>
      </auth>
      <source protocol='rbd' name='nebula-public/one-76-382-0' index='2'>
        <host name='10.8.11.1' port='6789'/>
        <host name='10.8.11.2' port='6789'/>
        <host name='10.8.11.3' port='6789'/>
      </source>
      <target dev='vda' bus='virtio'/>
      <alias name='virtio-disk0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
    </disk>