What does setting maprdb format plugin setting mediaType to "HDD" actually do?

[MarkRajcok]

https://docs.datafabric.hpe.com/61/Drill/override-maprdb-format.html states the following:

Drill is optimized for SSDs, however MapR Database and Drill can run on HDDs. If you run Drill and MapR Database on HDDs, use the mediaType option in the drill-override.conf file to override the default setting. The mediaType option accepts hdd or ssd (default) as the value.

We only have HDDs in our 40-datanode cluster.  We did not have this option set until recently (hence it was using the default "ssd" value).  After finding this in the documentation, we set it to "HDD".  We would like to know the following:

• How does Drill operate differently with mediaType set to "HDD"?  What is "better" when the mediaType setting matches the actual storage type?
• How can we verify that Drill is now operating differently (hopefully better)?

We opened support case 00102873 for this, but we're not getting satisfactory answers to the above questions.  So I figured I'd try the community forums.