'Clears CHAP credentials on a 3par volume.
Ignore exceptions caused by the keys not being present on a volume.'

def _clear_chap_3par(self, common, volume):

    vol_name = common._get_3par_vol_name(volume['id'])
    try:
        common.client.removeVolumeMetaData(vol_name, CHAP_USER_KEY)
    except hpeexceptions.HTTPNotFound:
        pass
    except Exception:
        raise
    try:
        common.client.removeVolumeMetaData(vol_name, CHAP_PASS_KEY)
    except hpeexceptions.HTTPNotFound:
        pass
    except Exception:
        raise
