title: Thread scheduler that can batch file operations on the same drive to the same thread?
body: <p>I'd like to use the Rx extensions to handle the parallelizing of long, file-bound operations.</p>
  
  <p>The workflow is something along these lines:</p>
  
  <ul>
  <li>search for a given file pattern on several drives (let's assume each drive is on a separate physical device)</li>
  <li>for each matching file found, queue the long file operation <em>to the same thread as for the other files on the same drive</em> - hopefully minimizing random seeks.  </li>
  <li>operations on files on different drives should be queued to different threads to allow for parallel processing. </li>
  </ul>
  
  <p>My question is: What Rx scheduler (or combination of schedulers) should I use ?</p>