title: AWS DMS replication instance out of memory
body: <p>I recently started to work with AWS Data Migration Service (DMS) and running into some issues. </p>
  
  <p>Currently attempting to migrate a 10GB Oracle DB to AWS RDS Postgres. Works but has crazy(?) memory requirements. Feels like it loads the entire DB into memory... Started with  <code>dms.r4.large</code> (15.5GB) but <code>can not allocate memory</code> after approx. 98%.... Will run smoothly with <code>dms.r4.xlarge</code> (30.5GB)</p>
  
  <p><a href="https://i.stack.imgur.com/rhiPq.png" rel="noreferrer"><img src="https://i.stack.imgur.com/rhiPq.png" alt="memory consumption during replication task run"></a></p>
  
  <p>As you can see in the screenshot (free-able memory, minimum), the instance is constantly running "full" before all memory gets released when the task finishes (or crashs).</p>
  
  <p>Is there any setting to change this and why does it behave like this? It makes the whole task unnecessary expensive...</p>