The GIS Hub web services have experienced unprecedented usage during North Dakota's on-going flood fight. During May the GIS Hub’s map services alone experienced over a million map image requests with most of those occurring during the last six days of the month. This corresponds to the beginning of the Bismarck-Mandan flooding which is still occurring as of this post. June usage was also high with the addition of the Minot flooding.
There was a corresponding surge in requests for map cache tiles although there were nearly eight million requests.
One of the main sources of this usage was the mapping tool that was made available by the North Dakota Department of Emergency Services. This application makes heavy use of the GIS Hub's base map data.
Although ArcGIS Server had been previously load tested it became clear that is no substitute for real use. We encountered a number of issues with the main problem being memory leaks in Windows Server processes. Eventually, we were able to implement configuration changes recommended by Esri that so far, have fixed the problems that were occurring.
Out of every struggle comes lessons learned. Hopefully it will be a while before we do more learning.
On a related note, if you have used or tried to use the GIS Hub during past and present flood fighting efforts and have ideas on how we could improve, please let us know, thanks.