'Create a volume entry in the DB.
Return the entry ID'

def _create_volume_db_entry(self, display_name='test_volume', display_description='this    is    a    test    volume', status='backing-up', previous_status='available', size=1, host='testhost'):

    vol = {}
    vol['size'] = size
    vol['host'] = host
    vol['user_id'] = str(uuid.uuid4())
    vol['project_id'] = str(uuid.uuid4())
    vol['status'] = status
    vol['display_name'] = display_name
    vol['display_description'] = display_description
    vol['attach_status'] = fields.VolumeAttachStatus.DETACHED
    vol['availability_zone'] = '1'
    vol['previous_status'] = previous_status
    volume = objects.Volume(context=self.ctxt, **vol)
    volume.create()
    return volume.id
