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Queue of remote probe is caching measurements?



Hi, we had the problem that our core server was poorly accessible for about 5 hours due to network problems. So all remote probes were not able to transfer data correctly or at all to the core server. Now we have a gap on the core server over this 5 hours on all sensors. I thought that the remote probes are caching it's data for that 5 hours and submit the cached data when the core server is reachable again. One remote probe has 5 Sensors with low frequented scanning interval (30 seconds for NetFlow V9, SNMP Traffic and Core/Probe Health, 30 minutes for 2 windows services), so there's not much data to cache I guess. Currently we have 70 Remote Probes online.

Any Ideas why the missing data in the mentioned 5 hours was not cached by the remote probes?

greetings, mike

cache queue remote-probe

Created on May 19, 2011 8:23:43 AM

3 Replies



Dear Mike,

PRTG's Remote Probes can buffer a maximum of 500,000 sensor results in RAM memory of the remote probe system (this is up to 50 - 200 MB of monitoring data). However, data is only stored in RAM memory. In case the system running the Remote Probe is rebooted, monitoring data in the buffer gets lost. I assume this was the case here.

Created on May 19, 2011 2:39:10 PM by  Daniel Zobel [Product Manager]



No because none of the 70 remote probes have submitted any results. It's not likely that all servers did a reboot within that time - I'm actually sure. In my opinion either caching didn't work or sending/receiving the cached data was unsuccessful. Is there something to configure for caching the results?

Created on May 19, 2011 3:10:12 PM



This might be just a caching issue. Please try the following:

  • Stop both PRTG services (core and probe).
  • Head to your data folder (can be discerned from the PRTG Server Administrator tool, under the Core Server tab)
  • Delete the PRTG Graph Data Cache.dat file
  • Restart the PRTG services
  • Log in to the Web GUI
  • Go to Setup | System Status and check the background tasks. It should state that it is calculating historic data


  • Refresh the page from time to time (is the number being reduced?)
  • Let it run until it is done and then take a look at the historic data of your sensors - it should now be available

Created on May 19, 2011 3:25:01 PM by  Daniel Zobel [Product Manager]

Disclaimer: The information in the Paessler Knowledge Base comes without warranty of any kind. Use at your own risk. Before applying any instructions please exercise proper system administrator housekeeping. You must make sure that a proper backup of all your data is available.