When you first create your ArcGIS Server site in Manager, you specify a folder to house the configuration store. The configuration store contains all the essential properties of the site, including information about the machines and clusters participating in the site. The configuration store is critical to the health of your site, and should be created in a redundant storage location if supporting mission-critical applications.
In a site with one GIS server, the configuration store can be specified to reside on the same machine that is running ArcGIS Server. By default, this location is <ArcGIS Server installation directory>/arcgis/server/usr/config-store. In a site with multiple machines, the GIS servers need to access the configuration store through a shared network directory. If desired, you can isolate the configuration store from the GIS server machines by placing it on a dedicated file server. This is helpful in some cloud deployments where the architecture needs to be flexible enough for any GIS server to go offline at any time.
You can change the location of the configuration store at any time using ArcGIS Server Manager or ArcGIS for Desktop. Refer to the related topics below for full instructions.
When expanding from a one-machine site to a multiple-machine site
If you are expanding your site from one GIS server to multiple GIS servers, you'll need to use your operating system tools to share the folder containing your configuration store and ensure that the ArcGIS Server account has permissions to read and write to the configuration store. For full instructions on this process, see the topic Expanding from one GIS server to multiple GIS servers.