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Gap in PRTG Graphs (no outage?)



My PRTG Graphs have gaps, and worse, aren't displaying as outages when they're down.

This is a ping graph as you should be able to see, and our internet dropped at 4:00.39 and we didn't see another ping until 4.04.29 and a few other times after that.


As you can see there's no data that comes thorugh but rather than report downtime, it's just empty! How can i change this?

I'll explain the situation in case i've gone the wrong way:

My home site support multiple sites branches. These branch sites use data at my home site. My Home site being down means no branch sites can use data, so we spend a fair bit on the ISP.

We also monitor branch sites, each router at the site branch is a little linux box so they are giving prtg pretty nice independant stats. If a single branch site is down that's not so bad. But a home site being down is essentially all branch sites down. On average each month, home site has about 99.99x% uptime, but our site branches have much less (99%-99.9%).

At the end of each week we want to have a report that would show ping time average/max packet loss, and downtime (where downtime is no response received in some arbritrary amount of time).

Also when our home site is down we want to be alerted promptly that there is a problem.

Any help configuring this is appreciated.



data-gaps graphs prtg

Created on Nov 18, 2013 7:04:16 AM

6 Replies



What looks like may be happening here is that the server may be synchronizing it's time to another server and it's making some big jumps so there are large gaps in the data. I would firstly suggest to take the PRTG server off of synchronizing with any NTP server and see if you get better results.

Those reports you could do by putting all of the Ping sensors into one report and each one would tell you the downtime for the sensors. The one issue that I see is that if you are monitoring from your home site, that if the connection goes down to the remote sites, PRTG will not be able to contact them so they would show as being down only because the home site is down. In this case, what you may want to do, if it's possible, is to install remote probes at the sites to have them check internet capability separate of the connection to the home site, that way you will know what part of the system failed. The Remote Probes will continue monitoring for 500,000 requests after the connection to the core server goes down so when the connection comes back up, there won't be superfluous downtime shown in the reports.

Created on Nov 18, 2013 4:49:40 PM by  Greg Campion [Paessler Support]




I read this in several other responses to similar questions, but no, it's not synchronizing it's time to another server, i can directly tell you that this directly correlates with an outage. Our internet at the home site was down during this period and so its more important than ever that these reports are right so i can submit it to the executives when I have to report on how and why for about 10 minutes none of our staff across 10 locations could access data.

In fact, if the gaps were an NTP server issue, still, where is my outage? Everyone in every branch was unable to connect for this 10 minute window of up/down internet. I would like to still report on that. There was a hail and electrical storm where I was and network and power went out.

Mind you, i've never seen a NTP server shift 4 minutes.

I understand how to make the report, however, none of these probes are reporting downtime, only when many packets are missing, there are large gaps in the data. I could just pull the ethernet cable out and replicate a real downtime, with the same gap in the graphs and no downtime.

I have seen this on every report so far since we increased the ping count per probe to above 1 per minute. When it was 1 per minute, a missing ping was reporting as an outage, but since we have more than 5 it does max ping, min ping, average ping, packet loss, and outage (but outage never happens).

To me it feels like there's a configuration issue where instead of reporting downtime, PRTG is instead just treating it like it's waiting.

Once we work out how to fill the gaps in the graphs, then I'll happily talk about the configuration of how to report better. But understand that a loss of connection to our home site, is an outage. If a branch can't see the home site then they can't work. So it's a literal outage for them from a business point of view. There's no point in calling that uptime because they can browse the internet. I don't want to know the internet status, I want to know their availability.

Created on Nov 18, 2013 9:44:29 PM



I don't know why that image doesn't work, but if i try to edit the post it gives me an error so here's the image again. http://www.tiikoni.com/tis/view/?id=3d96178

Created on Nov 18, 2013 9:57:45 PM



This may be related to overload on the server since it seems like the server missed scanning intervals for a few minutes here and there. In the chart that is in the picture, it is showing a scan at 4:00:39pm and then the next scan is 4:04:29 which is likely why you are seeing the gaps.

This is generally indicative of time changes but could also be overload or possibly scheduler issues causing PRTG to miss these scanning intervals since they should be happening every 30 seconds. Please send over a support bundle with your logs to [email protected] so I can take a better look at the details of this. Please reference this KB article in the bundle when you send it over.

Created on Nov 20, 2013 8:22:26 AM by  Greg Campion [Paessler Support]



Hi, During that period, we had an outage, a literal outage. It's monitoring our upstream provider, and it went down for that period, the provider came back online, using their backup backhaul, but the pings were bad because their backup had an issue. So they took it down and resolved the issue with the primary backhaul. That's why the pings go crazy too, because onsite we literally had an upstream backhaul issue.

It was a provider outage, but it shows as nothing on PRTG. I can't believe you are trying to argue that it's not an outage, that's not a question, it was an outage! A user seen outage, which was confirmed by the provider, witnessed by me onsite unable to connect to the internet.

I don't have a support pack option i can only ask a question or give feedback, is this because my support has expired after 12 months?

Created on Nov 20, 2013 10:29:05 PM



I'm honestly not trying to argue that it was not an outage, I'm saying that during that time, PRTG did not scan. If you had an outage for that time and PRTG was trying to ping out and was not able to, it should still scan and then report an error but it looks like during the outage that the scans were not run at all.

Is this sensor on a remote probe at another site that did not have connectivity to the PRTG server during the outage? It could be that since it was not able to report back the downtime since the link was down, it is showing that gap. You can also collect the logs and send them over if your version is an older version without the support bundle.

There is an option to upload the logs to our FTP-Server, using the button "Send Logs to Paessler..." on the tab "Logs" in the "PRTG Server Administrator" tool (see Windows start menu).

Please find detailed instructions in our knowledge base: https://www.paessler.com/knowledgebase/en/topic/7983

If you want to manually collect log files in order to send them via email, you will find the log files within the data directory as defined under the "Core Server" tab of the "PRTG Server Administrator" tool, or in the following default paths:

XP/2003: C:\Documents and Settings\All Users\Application Data\Paessler\PRTG Network Monitor\Logs (System)

Vista/2008/Windows 7: C:\ProgramData\Paessler\PRTG Network Monitor\Logs (System)

Please be aware that it might also be an additional folder named 'V7' or 'V8' in which the "Logs (System)" folder resides.

Created on Nov 21, 2013 9:58:02 AM by  Greg Campion [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.