protected function _set($key, $value, $ttl = null)
    {
        if ($ttl !== null) {
            $ttl = $this->_normalizeInt($ttl);
        }

        try {
            $this->_setData($key, $value);
        } catch (RootException $e) {
            if ($e instanceof InvalidArgumentException) {
                throw $e;
            }

            throw $this->_createContainerException($this->__('Could not set data'), null, $e, $this);
        }
    }