title: How to change AWS-RDS instance type without downtime?
body: <p>I'm using AWS-RDS(Aurora MySQL5.6) and It's a cluster, it has one writer instance and one reader instance. I find each instance would be down for nearly 10 minutes when I change its type, it's unacceptable, what should I do to avoid downtime?</p>
  
  <p>Here are more details information:</p>
  
  <ul>
  <li>Change type from db.t2.small to db.t2.medium</li>
  <li>Engine version: 5.6.10a </li>
  <li>Freeable Memory: 300M</li>
  <li>DB Connections (Count): ~400</li>
  <li>CPU Utilization (Percent): ~20%</li>
  </ul>