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How can I delete some bad data?



I am using PRTG to log SNMP bandwidth data from a Juniper SSG device. I cleared counters on the Juniper and the data logged during the corresponding 5 minute PRTG interval is crazy (e.g., a bandwidth spike on the serial interface of 700,000 kbps! As you'd guess, a spike of this size makes all the graphs rather useless).

I tried stopping the PRTG service, deleting the data folder for the date, then restarting, but graphs and data table (in the win32 app) still show the data.

I'm not sure if this is a data issue, or a graph/table issue.

data graphs prtg snmp spikes

Created on Jul 23, 2010 6:32:50 PM

Last change on Jul 26, 2010 9:56:36 AM by  Daniel Zobel [Product Manager]

3 Replies

Accepted Answer



Under the sensor channel options you can define a spike filter for individual sensor channels. Using this filter also works retrogressively, i.e. it will also filter historic data. If you define said filter you should be able to fix your graphs.

Created on Jul 26, 2010 9:40:25 AM by  Patrick Hutter [Paessler Support] (7,225) 3 3



Thank you for the feedback. I am getting some strange results and so it seems I am not setting the spike filter correctly.

The system I am running is PRTG v6.2.2.983. The method to reach the spike filter is slightly different from the one described in the link above: go to sensors, click on "edit," then Sensor settings->Advanced.

I check the box next to "Spike Filter" and enter 1600 (as this sensor is monitoring bandwidth on a T1). There is another column not pictured in the screenshot in the link referenced above, with radio buttons for "Divide" and "Multiply" and a field "to". Default radio button is "Divide" -- I am not sure what this means so I leave it at default settings.

When I enable this filter, the graphs become very strange and display only up to 12 kbit/second.

Here are two screenshots:

graph with the problem spike

sensor settings "advanced" dialog box and resulting graph

Thank you again for your help.

Created on Aug 11, 2010 6:26:20 PM

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.