Purpose of graph templates associated with a device template?

[andreas22]

Hi!

I'm new to Cacti.
Today I did a fresh Cacti 1.2.16 installation on a Debian 11 (bullseye) system with "apt install" using packages from the Debian repos. This went well without errors and Cacti was up and running in almost no time!

I then added about 20 devices using the provided "Local Linux Machine" device template. This template is associated with several "Graph templates" (which I think is a fine thing if it would work as expected )
I also added various other data queries like "Processor Information" or "Interface Statistics" to each device and subsequently added graphs for most of the data queries.
The graph templates already had graphs added, so I didn't have to do anything to get nice graphs.

These devices are various Linux servers in my local network. They come with different CPU, memory and work load.

But after a while and much to my surprise I noticed, that all the graphs from all devices which come from the graph templates show exactly the same data!
In fact it seems, that the graphs for all devices coming from the graph templates show the data collected from the first device I added.
The graph title shows the name of the device (the linux server hostname) as expected, but the data in the graph is wrong.
(And, of course, I double-checked the hostnames I used when I added the devices. They are correct for each device. The data from the data queries show plausible values coming from these machines)

As an example, the attached files show the memory usage of three of my Linux servers over the past 6 hours. The Linux servers are very different (maxwell is a 64 core / 256GB server, faraday is a 4 core / 8GB VM, planck is a 8 core / 32GB server) and it is not very likely, that the memory usage graph of these machines is exactly the same over a time period of 6 hours!

All the graphs coming from the graph templates associated with the device templates show this behavior (memory usage, load average, number of processes). The data in the graph seems to come from the first server I added to Cacti today.
The other graphs coming from the data queries I added to the device show plausible values, though.

How are "Graph templates" associated with a device template supposed to work in Cacti?
After reading the docs I expected the templates will just get filled with real data from the actual physical device, but obviously this is not the case here.

Is this a bug, an error in my configuration or do I miss something here?

Any idea, anyone?

- andreas

[TheWitness]

Local Linux machine is for the Cacti Server only. It's only there fore historical purposes. I would suggest you use the Net-SNMP device template instead.

From my perspective, one of the key advantages for Cacti is it's ability to discover the Device Types when using Automation. When you assign manually, you need to know what machine type you are working with. Device Templates include Data Sources and corresponding Graphs that could Possibly be useful for a Device. There is a setting to Test First to ensure that the Device in question actually includes the monitored item. For example, some families of Devices have Temperature and Humidity sensors, and others do not. In a modern Cacti install, maybe even a little newer than the one you are using, a single Device Template could include both Temperature and Humidity, and you would only end up with Graphs created for Devices that supported them.

The current Cacti is 1.2.22. Best to get there, and skip everything in between.

[andreas22]

Hi!

Many thanks for your reply!

Of course you are right.
I re-worked the whole configuration and with the Net-SNMP Device Template I now get associated Graph Templates which actually show correct data.

Obviously I did not realize what the word "Local" in the device template name meant when I first configured my Linux devices in Cacti. I just read "Linux Machine" and assumed, it would work for my use case.
Well, one should not assume...
(It seems that template entities in Cacti could make use of a new "description" or "comment" text field where one could describe the purpose of the template)

For now I have manually configured the devices in my local network. I did not use the auto-discovery feature, yet.
I will also stay with Cacti 1.2.16 for now, as this comes with the Debian 11 repos and I don't want to make things more complicated than needed.
Perhaps I will upgrade when I have learnt enough about Cacti.

Thanks again!

- andreas

[TheWitness]

So many things, so little time, very little staff unless you put me on a scale.