ArcGIS Server is a product built by ESRI that offers web-based editing and display of GIS data, as well as providing a high speed database for GIS data. ArcGIS Server is a replacement product for the older ArcIMS, which had similar, but not all, functionality of ArcGIS Server. In many senses, ArcGIS Server delivers what ArcIMS promised, and although it is still a complex product to understand and use, it has made great strides in useability from ArcIMS.
The latest version, version 10, was release as part of a product-line wide upgrade by ESRI in July, 2010. The new version of ArcGIS Server offers online editing (which version 9 did not), as well as multiple examples and an upgrade to their JavaScript and Flex APIs. It also has some cloud integration and allows publishing of datasets to ESRI's new centralized data repository: ArcGIS.com.
There are many companies and agencies in Alaska that use ArcGIS Server. Many use it for a simple GIS data repository, while others use if to show Alaska-based data sets over the web. Because ArcGIS Server is a complex product, we've had many clients come to us to help them setup and configure it.
Alaska datasets offer a unique challenge for ArcGIS Server: because the state is so large, reasonable performance over the web is difficult to attain. The main challenges for speed are background layers (usually rasters) and the number of published MXDs on the map. We've even done mapping for small portions of Alaska that have sub-meter ortho photos, and that is still a huge amount of data.
To be useful, background layers such as aerial photography or other raster datasets must go through a cache building process. This cache building is very CPU intensive. We have found that farming out the cache building to multiple computers or servers can speed up the process significantly (ask us for details, this is not a simple thing to setup). You also need to have the correct licensing level with ESRI for this to be effective.
A cache for ArcGIS Server consists of a pyramid of images at predefined zoom levels. If you are caching all of Alaska, you would probably want between 12 to 20 zoom levels for a well performing map. The cache functionality also allows you to build pyramids, but only in selected areas. You definate a selection polygon, and then build more a more detailed cache within just that area.
The other performance problem can be the number of layered MXDs you publish. Each MXD layer has the advantage of being able to be cached. But once a layer is cached, you cannot turn individual overlay layers on or off: this functionality is reserved for non-cached layers only.
Try to limit the number of overlying MXDs to 5 or less for best performance.
As with other GIS solutions, the speed of accessing data from the server can be an issue. Most Alaskan clients have found that either having the data local on the server, or available via gigabit ethernet on a high speed NAS can work.
If you have a smaller dataset, or just a portion of Alaska (such as a single city), you can get very good performance with local storage. Try using a 15k rpm drive or even better, a solid state drive (SSD). An SSD can also make a good performance boost for ArcGIS Server's running speed.
GeoNorth is a full service GIS consulting company. We offer needs assessments, strategic planning, gap analysis, development, implementation, training, and more. For a list of our services, please see our GIS services page.
If you'd like assistance or guidance with your ArcGIS Server implementation, please give us a call at our Anchorage, Alaska office at 907-677-1500