암호화된 세션 및 CI 프레임워크 로그인 시 세션 사용 시 주의할 사항

$sessionData = array(
'username' => $username,
'password' => $password,
'time' => time()
);
$this->session->set_userdata($sessionData);

$this->session->userdata("xxxxxxxxx"); (userdata中放取出的字段)

$config['sess_save_path'] =BASEPATH.'../'.'session_file';

A PHP Error was encountered 
Severity: Warning Message: mkdir(): Invalid path 
Filename: drivers/Session_files_driver.php Line Number: 117 
Backtrace: File: /Library/WebServer/Documents/CI/cinews/ci/index.php
Line: 316 Function: require_once