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Windows Physical Disk I/O Sensor weird behavior



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We are very happy about the Windows Physical Disk I/O Sensor. We use it to detect sudden slow downs in Avg Transfer Time. After the latest update, an odd behavior started to occur.

At a random time out of office hours, ALL Disk I/O sensors monitoring actual physical servers, will skyrocket from an average of 0,005 to about 1,500. Disk I/O sensors on virtual machines does not skyrocket at some random point. If I pause these sensors and resume them again, they return to their original average of 0,005.

I noticed that a change to these sensors has happened in the latest update, so I took the time to remove all our Disk I/O sensors (About 200 of them) and re-add them. The incident still occurs.

Any known bugs?

Kind regards, Thomas Schmidt

disk-io physical-disk prtg wmi

Created on Sep 29, 2016 6:15:15 AM by  Thomas Schmidt (27) 1

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Hi Thomas,

Please enable "Write result to disk" in one of the affected sensor's "Settings" tab. With the next scan it will write one or several result-files into "C:\ProgramData\Paessler\PRTG Network Monitor\Logs (Sensors)" of your PRTG server (or on the Remote Probe if applicable). All files have the sensor's numeric ID in their filenames. The sensor ID can be found on the sensor's "Overview" tab.

Those files will be overwritten with every scan. Please save one batch of the outputted files when the result is as expected. Then click on the channel that gets these "spikes" and enable an error-limit so that it will go into error state when the result is highes as expected. As soon as this happens, save away the written result files so we can compare them. I assume however that the value is reported like this from the device itself, but we can check this way just to be sure. Send them to [email protected], subject Windows Physical Disk I/O Sensor weird behavior (Case PAE764251)

In case the device reports it like this, you can also enable the so-called Spike Filter in the settings of the channel to disregard such readings.

Kind regards,


Created on Sep 30, 2016 11:16:12 AM by  Erhard Mikulik [Paessler Support]

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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.