In a multiple-machine site, load balancing is handled among all GIS server machines in a single cluster using ports 4004 and above. If your site uses a single cluster, all GIS servers in the site will load-balance requests. If your site uses more than one cluster, load-balancing is handled among all GIS servers within each cluster. Essentially, clusters are independent groups of GIS servers that run dedicated sets of services.
For example, an incoming request is assigned to an available GIS server in the cluster, even if the request was directed to a specific machine within or outside of the cluster. That GIS server then does the work of drawing the map, finding the address coordinate, running the geoprocessing tool, and so on, and returns the result to the client. If a machine is offline or the service that was requested is running in a different cluster, the request is forwarded to the cluster containing the service. The GIS server machines in that cluster load-balance and process the request accordingly.
In large sites with a single cluster, you can configure the site to remove the load balancing functionality between GIS servers. This reduces network traffic between machines in the site, reduces load on your network, and helps improve monitoring of GIS servers in your site.
To remove load balancing, the following criteria must be met:
- All GIS servers in the site must participate in a single cluster. Multiple clusters cannot exist.
- An external load balancer or ArcGIS Web Adaptor must be configured to forward requests to the GIS servers in the site. If no external gateway exists, requests will only be handled by the GIS server designated in the request.
Follow these steps to remove load balancing:
- Open the ArcGIS Server Administrator Directory and log in with an account that has administrative privileges to the site. The Administrator Directory is typically available through a URL such as http://gisserver.domain.com:6080/arcgis/admin.
- Click system > deployment > update.
- Click the Single Cluster Mode drop-down dialog box and select TRUE.
- Click Update. All GIS servers in the site are restarted.
After the GIS servers restart, load balancing will no longer occur between machines in your site. If you haven't done so already, configure an external load balancer or ArcGIS Web Adaptor to forward requests to the GIS servers in your site.
To turn on load-balancing, set the Single Cluster Mode to FALSE.