private function convertToBytes($strSize)
    {
        switch (strtolower(substr($strSize, - 1))) {
            case 'm':
                return (int) $strSize * 1048576;
            case 'k':
                return (int) $strSize * 1024;
            case 'g':
                return (int) $strSize * 1073741824;
            default:
                return $strSize;
        }
    }