'Return copy method(FULL or THIN).'

def get_copy_method(self, metadata):

    method = metadata.get('copy_method', self.conf.vsp_default_copy_method)
    if (method not in _COPY_METHOD):
        msg = utils.output_log(MSG.INVALID_PARAMETER_VALUE, meta='copy_method')
        raise exception.VSPError(msg)
    if ((method == 'THIN') and (not self.conf.vsp_thin_pool)):
        msg = utils.output_log(MSG.INVALID_PARAMETER, param='vsp_thin_pool')
        raise exception.VSPError(msg)
    return method
