Comment 1 for bug 1075971

Since it is now possible to both boot instances and attach volumes without specifying device names after https://blueprints.launchpad.net/nova/+spec/improve-block-device-handling BP has been implemented. in which case the device names will be handled properly by Nova.

It is still possible to supply device names (for backwards compatibility's sake), which would cause the same behavior as described above. This is really an issue due to the fact that there is no way to make sure libvirt uses the same device name as supplied to it since libvirt only takes this as ordering hints. the best solution really _is_ to rely on Nova to actually choose the device name as per implemented BP.