Comment 4 for bug 1067214

The code below will run in nova-api if nova-compute failed.
=========================
if is_up == False:
    # If compute node isn't up, just delete from DB
    LOG.warning(_('host for instance is down, deleting from '
               'database'), instance=instance)
    self.db.instance_destroy(context, instance['uuid'])
==========================

if so, the resource like fixed-ip, floating-ip, volumes will be unavailable forever, and quota maybe wrong.