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What is the meaning of Uptime in Reports



Hi I have a sensor measuring the time taken to run a process. For most of the time, there are no processes running and timetaken = 0 It has an Upper Error Limit level set to 1 hour.

I created a "Top 10 Uptime" report including only this sensor

I run the uptime report for a 1-week period and i see:

Uptime [%] -- 99,031 % Uptime [s] -- 3d13h9m11s Downtime [%] -- 0,969 % Downtime [s] -- 50m0s

Now i'm just trying to understand these column headings..

Uptime [s] - does this mean the time in the last week where the sensor was:

  • nonzero
  • not above Upper Error Limit

Downtime [s] - does this mean the time in the last week where the sensor was:

  • time above Upper Error Limit



downtime reports uptime

Created on Aug 18, 2016 11:48:40 AM

4 Replies



Update: Corrected answer below

Hi there,

The uptime/downtime you're referring to is not depending on limits configured in a sensor causing it to go into an error state. As soon as you have at least two consecutive failed scans (device not reachable for example leading to the sensor getting no result), the time-frame between those scans is regarded as downtime that's being subtracted from the uptime. See also this thread about the correlation between up- and downtime.

Kind regards.

Created on Aug 19, 2016 12:08:13 PM by  Erhard Mikulik [Paessler Support]

Last change on Sep 7, 2016 5:48:07 AM by  Erhard Mikulik [Paessler Support]



Hi Erhard

Ok many thanks for the explanation and the article reference

So is there anything that tracks the percentage of time a sensor stays in Error state or Warning state over e.g. the last week/month/year? This is much more useful for me.

Also, just to make it more confusing,... when i run my "Top 10 Uptime" report with UpperErrorLimit = 1hour, i get a different Downtime/Uptime result to when i set UpperErrorLimit=2 hours.

If Downtime/Uptime value is only related to failed sensor scans (not sensor error state) then shouldn't the test above return the same result?


Created on Aug 19, 2016 12:27:15 PM



I'm afraid there is no report about how many times a sensor hit a limit defined in the sensor. This sort of information is found for every sensor in its "Log" tab, which you can also generate an XML of, but there's no automated report focused on how many times a sensor hit a limit in one of the channels.

I'm not sure about your other question about "Top 10 Uptime" and upper error limits. Screenshots would be great here to see what you are referring to. It might be easier if you contact us by email about that ([email protected]; use Case PAE745913 in the email's subject, so the mail gets connected to this thread and reaches me directly to further work on it).

Kind regards.

Created on Aug 22, 2016 2:33:26 PM by  Erhard Mikulik [Paessler Support]



As discussed per email, I need to correct my former statement, because I misunderstood something myself about this: A series of consecutive "down" scans due to limits defined in the sensor also reflects as downtime in graphs and reports, since PRTG does not distinguish between "down because of sensor limit" or for example "down because device could not be reached". So basically every period of consecutive "down scans" will reflect as downtime.

Sorry for the confusion & kind regards.

Created on Sep 7, 2016 5:47:18 AM by  Erhard Mikulik [Paessler Support]

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