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Why does my WMI Logical Disk sensor show values above 100%?



I monitor a logical disk via Windows Management Instrumentation. The channels % disk read time and % write time frequently exceed 100%. Is this an error or is there another reason for this issue?

disk logical-disk prtg sensor uncommon wmi

Created on May 27, 2013 3:49:41 PM by  Gerald Schoch [Paessler Support]

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Accepted Answer



This article applies to PRTG Network Monitor 13 or later

The Reason for Disk Time Channels Above 100%

The WMI Logical Disk sensor shows, amongst other values, read and write times on logical partitions of a disk drive. It is neither an error by PRTG, nor a quite unusual behavior that these time counters exaggerate disk time.

In general, reported disk utilization can exceed actual utilization because busy time is reported based on the duration of a request. This includes also time spent in other activities. All busy time is summed up for all requests and divided by the time of the sample interval. If there are multiple requests processed at the same time, the total request time can be greater than the time of a sample interval. Thus, values of these sensor channels can exceed 100%.

For details, please refer to the following article in Microsoft’s TechNet:

Created on May 27, 2013 3:51:38 PM by  Gerald Schoch [Paessler Support]

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.