Re-posted with permission from System Management by Exception.
Any good reporting should be fully automated and web-based with no more then 2-3 levels of drill-downs and the highest level should be a color-coded dashboard. So what is the best mean for color-coded dashboard? Nowadays the tile (heat) chart is getting more and more popular for that purpose!
The original source of the tree-map idea: Treemaps for space-constrained visualization of hierarchies by Ben Shneiderman
CMG has published several papers about tree-mapping of capacity usage metrics:
Blog Resource: http://www.trub.in/2014/02/tree-map-heat-chart-tile-chart-is-good.html