We're evaluating ArcGIS Monitor and from the settings and reports the use of 'Max Free', 'Min Free' and 'BusyInstancesMax' is confusing.
The documentation says that "when Max Free and Max Instances are equal, you should consider increasing the number of instances on the service". And in fact the reports flag those case where Max Free and MaxInstances are equal. That makes it seem like Max Free = the Max # of busy instances for the service, i.e. "busy" instances and not "free" instances. If that's the case, what does "Min Free" mean? To make it more confusing, when the condition is met and flagged in the reports, the Comments say "Warning: Max instances too low (Busy or Free equal Max). If available memory, increase min and max instances." Why would Free = Max be a warning condition of "business"??
What's more, 'BusyInstancesMax' is documented as the "Total maximum number of ArcGIS Server busy instances in the report time period". To me that means the number of times a service has maxed out its instances for the reporting period. If that's the case then by its own reckoning, I would expect that when Max Free = MaxInstances then BusyInstancesMax should be non-zero, but that's not what I'm seeing in the reports: some of those that are flagged are non-zero but some are zero as well.
What I"m trying to get to the bottom of is, how do I detect when the number of instances for a given service should be considered a candidate for increase? It seems like it's simply those that are flagged in the report with "Warning: Max instances too low (Busy or Free equal Max). If available memory, increase min and max instances", but at the same time I'm seeing 0's for BusyInstancesMax.
Can anyone shed clarification around this?