How to troubleshoot open requests on probe?

This sounds like the probe is having an issue handling the amount of WMI sensors that you have on the system. If you look in the probe logs you should be able to see what sensors specifically are timing out but most likely changing the scanning intervals on some of these sensors would solve the issue.

If you need to keep them on this interval, you could also consider deploying a remote probe These will help to load balance the WMI requests. This issue isn't really a resource problem in the traditional sense of RAM and CPU, it's more an issue with the WMI subsystem limitations on the server.

Another option with this in mind would be to change some of these sensors to only use Performance Counters in the windows compatibility options of the devices or group or to switch to another monitoring protocol like SNMP.

Thanks for the response, I'll definitely look into that. I'll let you know what the results are.

Is there a simple way in PRTG to show all WMI sensors? Or to tell if a sensor is WMI/SNMP?

All of my sensors were auto-discovered, and I am ok with switching them to SNMP. I am assuming this would be to manually delete the WMI sensors that were discovered and manually add SNMP sensors that track the same information?

This can be done by selecting the following from the menu:

You should migrate on a per sensor-type basis to avoid missing any :)

PRTG Scheduler | PRTGapi | Feature Requests | WMI Issues | SNMP Issues

Kind regards,
Stephan Linke, Tech Support Team

I had too many open requests in one of my remote probes, but could not find the log file contains sensors specifically are timing out.
Would you please say the path of that log file a little more detailed?

You will first need to generate the log files on the probes. For that open the PRTG web interface and navigate to Setup>System Administration>Administrative Tools and click on Go! under "Write Probe State Files". Afterwards you can find the log files on the system running the affected probe under:

C:\ProgramData\Paessler\PRTG Network Monitor\Logs\debug

Kind regards,
Sasa Ignjatovic, Tech Support Team

In this given scenario of wanting to see which WMI probes are taking too long, which file in the Logs\debug do you look at to verify it. Is there a pattern to search in these logs that will show which sensors are taking too long?

You would want to check the "Probe State (Scheduler Debug Data)" file. In it the "Timing's" are important. You should check if any sensors need unusually long, or if they even need longer than their set scanning interval. Also, in the "Probe State (Global Debug Data)" file you can check if any of the devices report any WMI errors.

Kind regards,
Sasa Ignjatovic, Tech Support Team