Currently I do setup monitoring-service for our Server.
I've found some articles, which recommend to use: Netdata, prometheus and grafana
So I wonder what are the benefits to use all three of them. Can anybody explain it to me, why prometheus and grafana is recommended, if it's seems that netdata do the same stuff as those both?
Even at the netdata-documentations, there are an article about the setup for this: https://learn.netdata.cloud/docs/agent/backends/prometheus/#filtering-metrics-sent-to-prometheus
What are the benefits of this constellation?
In summary, Grafana will display metrics collected by Prometheus from netdata.
There's no benefit to rolling out a stack like that except that Prometheus has scaling capabilities that has made it ubiquitous so if you already have netdata and want to modernize your stack, you can use it together with Prometheus.
If you're starting from scratch, I'd recommend sticking to Grafana + Prometheus + Prometheus' node exporter. This will give you about the same metrics but is "atomic" in that each does a single thing well, and each component is independant so you can administer each one without (exceedingly) impacting the others.
I would suggest, that if you are just starting out, a combination of the Netdata Agent + Netdata Cloud has you covered.
You install the Netdata Agent on every computer that you wish to monitor and you use Netdata Cloud as the unified pane of glass to view the entire infrastructure in a "centralized" way. Note that the data are stored locally, on every node, and they are streamed THROUGH cloud to your browser directly.
If Netdata monitors whatever you need, I don't see the reason to spend time in setting up Prometheus and grafana, as Netdata will give you everything (data-collection, alerts, charts) out of the box.
You can enable exporting in case you want to archive metrics for a long-time (say 6 months+). In that case,you can export every 60s to save up space, while Netdata will keep the per-second metrics for the near term.
Disclaimer: I work at Netdata