Low isolation and maximum number of instances

[KubaSzostak1]

I have read Tune and configure services—Documentation | ArcGIS Enterprise but still I need some clarification. What happens with pooling when I set in Processes section low isolation? 

Processes section

Instances per process (low isolation only): 8

 

Pooling section

Maximum number of instances per machine: 4

Does it means there will be only one ArcSOC.exe process for this service? As I guess there will be 4 instances in one ArcSOC.exe process .

Maximum number of instances per machine: 12

Does it means there will be 2 ArcSOC.exe processes for this service? As I guess there will be 8 instances in one ArcSOC.exe process and 4 instances in second ArcSOC.exe process.

[JonathanQuinn · Accepted solution]

The quickest answer is don't use low isolation. It's unstable and will be removed from the software eventually.

A more complete answer is described in earlier versions of the help. The Isolation section has been removed because we discourage its use:

Tuning and configuring services—Documentation | ArcGIS Enterprise

[RandallWilliams]

Piggy backing on Jonathan Quinn‌, people used to use low process isolation to try to 'do more with less', basically, to squeeze more running instances out of processes running on the GIS Server. These days, the better solution is to add more memory to the ArcGIS Server host and keep processes in high isolation. 

[FinnianO_Connor]

Randall Williams‌ Jonathan Quinn‌ In a federated ArcGIS Server I do not see the option to change/set the isolation level. Is this expected behaviour? And if so, can I assume that all processes are running in high isolation?

Thanks,

Finnian

[RandallWilliams]

You're not crazy - this option to set processes to low isolation is just so *NOT* recommended that we removed it at ArcGIS Enterprise 10.5. It's not in the doc that Jakub referenced above, but you'd see it in the 10.4 doc. 

Tuning and configuring services—Documentation | ArcGIS Enterprise 

[FinnianO_Connor]

Good to know, thanks. Sometimes less options are easier to deal with!

[JamalNUMAN]

The “low isolation” option is still available in 10.7.1

The question is still valid: what does the instance per process mean?

We do understand that the number of instances per machine refers to the number of ArcSoc.exe that will be responding to the request on particular service, but how can we understand the instance per process?

[MoginrajMohandas]

"instances per process" means that you can assign multiple instances of a service to run under the same ArcSOC process. This is prone to stability issues, and we have actively discouraged it for some time now(hence the option disappearing from ArcGIS Server Manager), and will eventually be removed from the software. I would recommend trying out Shared Instances which is the new way to configure instances for your Map services. Introducing shared instances in ArcGIS Server 10.7  

[JamalNUMAN]

Hi Moginraj,

But what is the meaning of “multiple instances of a service”? I couldn’t feel the function of the instance!

If the process is the ArcSoc.exe, then what is the instance?

[KubaSzostak1]

The quickest answer is don't use low isolation. It's unstable and will be removed from the software eventually.

This is not an answer to my question but this is the answer I was looking for  

Thanks!