An ArcGIS Enterprise deployment is expanding one of its ArcGIS Server sites from one to three machines because some services now require additional…

The minimum number of instances for an ArcGIS Server service, whether using a dedicated or shared pool, is a per-machine setting. When an ArcGIS Server site is expanded from one to three machines, the service configurations are replicated across all machines in the site. Consequently, each of the three machines will run the specified minimum number of ArcSOC processes for every service. This results in the total minimum number of running ArcSOCs across the entire site being three times the original amount.

B. The same number of ArcSOCs will be running: This is incorrect because the minimum instance count is not a site-wide total that is distributed among machines. It is a setting applied individually to each machine in the site.

C. One and a half times as many ArcSOCs will be running: This is incorrect. The distribution of services between shared and dedicated instance pools does not change the scaling factor, which is directly proportional to the number of machines in the site.

1. Esri ArcGIS Enterprise Documentation. (2024). Configure service instance settings.

Section: "The number of instances"

Quote/Paraphrase: The documentation explicitly states

"The minimum and maximum number of instances settings are specified on a per-machine basis." This confirms that adding machines multiplies the total number of minimum instances by the number of machines in the site.

2. Esri ArcGIS Enterprise Documentation. (2024). About ArcGIS Server sites.

Section: "How a multiple-machine site works"

Quote/Paraphrase: This section explains that in a multiple-machine site

services run on all server machines within the site. It clarifies

"In a multiple-machine site

each machine has its own set of service instances to process requests." This supports the principle that instance counts are applied per machine.

3. Esri Training. (2023). ArcGIS Enterprise: Configuring a Base Deployment (Course materials).

Module: "Administering an ArcGIS Server Site"

Concept: The course materials detail that when a service is published to a multi-machine site

its configuration

including the minimum number of instances

is applied to each server participating in the site. Therefore

a service with a minimum of one instance on a three-machine site will have a total of three minimum instances running (one per machine).