In NetApp storage systems the root aggregate contains the root volume. The root volume contains special directories and configuration files for managing and controlling the storage system. The management and control operations might result a large amount of activity in the root aggregate. When you query the Insight system for the top 10 internal volumes with the highest IO density, your results might include NetApp root aggregates as members of the top 10.
When monitoring your environment it is more important to determine which internal data volumes are producing high I/O density numbers. In order to accurately identify only the data volumes, you need to isolate the NetApp internal volumes from queries you use to monitor I/O density.