1. If you use Amazon RDS, especially micro plan,
    remember to set $config['pconnect'] = FALSE in application/config/database.php.
    Because RDS has Max_connection limits.
  2. If you use RDS, remeber that the system timezone in RDS is +0 timezone.
    In your application, you should care about this thing.
  3. If you will use loadbalancer, remember to ….(???)