Clarification on ArcSOCs.

[Yogesh_Chavan]

Hi,

I wanted to understand how ArcGIS Server ArcSOC's distribution works across multiple machines.

We have HA 11.4 Enterprise deployment, with ArcGIS Server on 2 machines(Site + Joined Site). What I am trying to understand is how does ArcSOC instances gets distributed across the two server machines.

For example: We have a machine critical geocoding service with min and max instances both set to 40.

So the query I have is:

If we have set Minimum Instances set to 40, we observe 20 instances on machine A and 20 instances on machine B. So, is this a correct observation? How is ArcSOCs designed to be distributed? 20 Per machine(Total 40 for 2 machines) or 40 Per machine(Total 80 for 2 machines)?

https://enterprise.arcgis.com/en/server/11.5/deploy/windows/anticipating-and-accommodating-users.htm....

Thanks!

[ReeseFacendini_MadCo]

With your setup of 2 ArcGIS Server nodes (machines), the total number of instances would be double what was configured in Pro when publishing. By setting 40 instances for min and max, it would end up being 80 when reviewing the service in Server Manager.

If you wanted 40 instances total, you would publish with the min and max instances set to 20. 

Hope that helps

[Yogesh_Chavan]

Thank you @ReeseFacendini_MadCo 

[Priya_Das · Accepted solution]

Hi @Yogesh_Chavan 

In an ArcGIS Server multi-machine site, each machine runs its own pool of ArcSOC processes for each service. The minimum number of instances and maximum number of instances you configure for a service apply per machine, not across the entire site.

1. Plan per machine capacity — The service settings should consider RAM and CPU availability per server.
2. Multiply by number of machines — Total ArcSOC count = per machine × number of machines.
3. Monitor ArcSOC usage — Use ArcGIS Server Administrator Directory (/admin) or logs to see actual usage.
4. Avoid excessive min instances — High min values can consume memory even if idle.

If you’re observing 20 on each machine instead of the full 40:

• The service may not actually be honoring the configured minimum due to:
  • Publishing or config not updated — the service might have been restarted with a lower min setting.
  • Machine resource limits — ArcGIS Server may reduce the number of prestarted instances if there is insufficient memory or CPU.
  • Observation method — If you’re checking via Task Manager or ArcGIS Server logs, you might be seeing only active instances, not idle prestarted ones.
  • Shared instances — If the service is configured to use the shared instance pool (available for map services), the min/max instance settings don’t apply in the same way.

[Yogesh_Chavan]

Hi @Priya_Das,

Thank you for taking out your time to review this.