gzencode and save archive

function gz_archive($file_path, $output_file, $level = 5) {
  $buffer = '';
  $gz = gzopen($output_file, 'wb' . $level);
  $file = fopen($file_path, 'rb');
  while (!feof($file)) {
    $buffer = fread($file, 10240);
    gzwrite($gz, $buffer);
  }
  gzclose($gz);
  fclose($file);
}