private function logFailure()
  {
    if ($this->_debug) {
      printf("[LoadBalancer] Failed for %s<br />\n", $this->_connectionStrings[$this->_lastReturnedIndex] . (isset($this->_storageNames[$this->_lastReturnedIndex]) ? '|' . $this->_storageNames[$this->_lastReturnedIndex] : ''));
    }
    $hash = md5($this->_connectionStrings[$this->_lastReturnedIndex] . (isset($this->_storageNames[$this->_lastReturnedIndex]) ? '|' . $this->_storageNames[$this->_lastReturnedIndex] : ''));
    touch($this->_statusFilePrefix . $hash);
  }