What does the Headroom graph show?
The Headroom graph is related to remaining performance capability for the storage array controllers. This graph is visible on the Home page and on the Physical View tab of the Performance tile.
The Headroom graph shows the remaining performance capability of the physical objects in the storage system. Hover your cursor over a point on the graph to view the percentages of IOPS and MiB/s capability remaining for controller A and for controller B.