Why doesn't nova use virtio networking by default?
- Keywords:
- virtio kvm libvirt xml
We've realized that all instances booted with nova-compute on any node, are booted with 100Mb RTL interfaces, en we are seeing this line in libvirt.xml for any instance :
<interface type='bridge'>
<source bridge='br100'/>
<mac address=
<!-- <model type='virtio'/> CANT RUN virtio network right now --> <-- THIS LINE
So, how to we enable virtio model or e1000 model for a performance boost on nova using kvm ??
You can remove the comments around the line. There are issues with nova-volume and virtio net and some older kernels. Specifically lucid and centos 5.5. If you are not using nova-volume or those guests you should be able to uncomment that line with no issues.
To change new instances, change virt/libvirt.
To change running instances, change the libvirt.xml file in the instance's directory (/var/lib/
virsh destroy instance-xxx
virsh undefine instance-xxx
virsh define libvirt.xml
virsh start instance-xxx
Lucid guests will be fine as long as you don't try to dynamically attach a volume to them. If you need attachable volumes you have to use maverick+