function getHashDir($key, $level = 2) {
	$hash_dir = array();
	$hash_arr = str_split(sha1($key), 2);
	for($i = 0; $i < $level; $i++) {
		$hash_dir[] = $hash_arr[$i];
	} 
	$dir = str_replace('\\', '/', implode(DIRECTORY_SEPARATOR, $hash_dir));
	return $dir;
}