Comment 2 for bug 821466

Can you confirm that you are running a virtual kernel flavour? This is not immediately visible from the messages here. The difference would be that for -server the xen_blkfront driver is built as a module while -virtual got it built-in. So when booting a -virtual kernel, you will see no module loaded but /proc/devices should show xvd. Does cat /proc/partitions show anything?