I am a fairly new user of OpenStack using Ubuntu 12.04 with the cloud archive enabled to get Grizzly. I have managed to run a distributed node setup with KVM and libvirt by following this guide, but now that I try to setup a compute node with Xen and Libvirt I cannot make it work. I know that the supported and suggested way for Xen hypervisor is to either use XCP or Citrix XenServer, but the documentation says that it is possible to manage Xen using libvirt (This would be necessary for any Xen-based system that isn't using the XCP toolstack, such as SUSE Linux or Oracle Linux) and I need to try this solution instead (I tried XCP as well and I didn't manage to make it work properly on top of Ubuntu either, but even if I did, I would eventually try to use libvirt).

When I try to boot a CirrOS instance in the Xen based compute node (nova boot --image <id-of-cirros-image> --flavor m1.small --availability-zone nova:xennode1 TestXenHost) the spawning fails and instance boots in one of the KVM nodes. The error I get from the logs is this: error from xen daemon: (xend.err 'Device /dev/xvdp (51952, tap) is already connected.')

I found some people talking about blktap module, but I installed blktap-utils and blktap-dkms packages, and made sure the blktap module is running (lsmod).

Here you can find some pastebin links with the nova configuration files and logs: nova.conf, nova-compute.conf, nova-compute.log, libvirtd.log, xend.log

Can anyone say what is wrong here and if there is any rescue?

Thank you!