title: Is it possible to scale up/down Aurora RDS Cluster without downtime?
body: <p>I have RDS Aurora PostgreSQL cluster with two instances:</p>
  <pre><code>cluster
  ├── instance_1 [writer] [no multiAZ]
  └── instance_2 [reader] [no multiAZ]
  </code></pre>
  <p>When I changing instance type for <code>instance_1</code> failover operation working correct but I have downtime about 1~2 minutes. I checked downtime by running</p>
  <pre><code>watch -n 3 &quot;psql -h db.cluster.url -p 5432 -d postgres -U postgres -c 'select ID from TABLE limit 1'&quot;
  </code></pre>
  <p>After that <code>instance_1</code> becomes <code>reader</code>.</p>
  <p>Is there any way to change <code>instance_1</code> to reader manually, change it type and revert to writer without long downtime (no downtime is the best, but 5~10 seconds also acceptable)</p>
  <p>I know that I may use multiAZ instances but it will be cost twice expensive.</p>