Code review comment for lp://qastaging/~rackspace-titan/nova/xen_vmops_rescue_fixes

Hm. Did you try doing the unplugging/VBDs destroy after the rescue instance is shutdown? If that still gives 'device in use'.. that'd be pretty strange.

Ie, I was thinking if you restore _destroy_rescue_vbds() and just change the order in _destroy_rescue_instance() to the below, it should work?

def _destroy_rescue_instance(self, rescue_vm_ref):
    """Destroy a rescue instance."""
    self._shutdown_rescue(rescue_vm_ref)
    self._destroy_rescue_vbds(rescue_vm_ref)
    self._destroy_rescue_vdis(rescue_vm_ref)

I also noticed that _destroy_vdis() and _destroy_rescue_vdis() are very similar (I know you didn't modify them)... the former waits for the vdi destroys to complete. I wonder if those could be consolidated as a part of this, even though it's somewhat unrelated.