Monitoring: Software comparison & IT system monitoring

Table of contents 

1. Monitoring: Software comparison and IT system monitoring explained
2. Definition: What is monitoring?
3. IT system monitoring: Monitoring digital infrastructure
4. Why IT system monitoring is indispensable today
5. Monitoring software comparison: Icinga, Checkmk, and Nagios
6. CMDB and monitoring: The perfect combination
7. Monitoring integration with i-doit: Solution for IT documentation and monitoring
8. Ensuring stable IT infrastructures with monitoring

Monitoring: Software comparison and IT system monitoring explained 

When server problems, network bottlenecks, or outages of business-critical services occur, IT must react immediately. A well-known study by Gartner shows just how expensive such disruptions can be: As early as 2014, companies lost an average of around 5,600 US dollars per minute or 300,000 US dollars per hour due to IT outages.

This is precisely where IT system monitoring comes into play: It monitors the availability, performance, and security of your IT infrastructure and raises the alarm before initial anomalies escalate into severe disruptions. In combination with centralized IT documentation, this creates real added value: You can see which services are affected, what dependencies exist, and who is responsible.

Learn how monitoring works technically, how monitoring software compares, and how you can seamlessly integrate it into your existing IT environment with i-doit.

Definition: What is monitoring? 

Monitoring is defined as the systematic supervision and observation of processes, systems, or states to ensure their operational functionality and detect deviations early. The term derives from the Latin "monere" (to admonish, to warn).

In practice, monitoring is used in various fields: from production monitoring in industry to medical monitoring in hospitals and environmental monitoring. The core technical principle remains identical: Relevant metrics are continuously recorded, compared against defined target values, and alarms are triggered when thresholds are exceeded.

IT system monitoring: Monitoring digital infrastructure 

IT system monitoring applies the monitoring principle to IT infrastructures. It refers to the continuous monitoring of IT systems, networks, applications, and services. The goal is to record the operational state of the IT infrastructure in real time, identify problems early, and send automated alerts in the event of deviations from the defined target state.

In doing so, IT system monitoring checks various parameters:

• Availability: Is the server, service, or application reachable (ping, port check)?

• Performance: How high is CPU utilization, memory usage, or network latency?

• Resource consumption: Are storage capacities, bandwidths, or licenses close to their utilization limits?

• Errors and warnings: Are there security- or operations-relevant log entries that point to problems?

Monitoring software combines three central approaches:

• Status-based monitoring: Checking the health of a system using defined thresholds (e.g., OK, Warning, Critical).

• Metric-based monitoring: Recording and analyzing time-series graphs for performance optimization and capacity planning.

• Log- and event-based monitoring: Filtering and correlating important events to trigger automated actions.

Why IT system monitoring is indispensable today 

Without monitoring, IT teams operate in reactive mode: Problems are only addressed when users report issues or systems have already failed. Professional IT system monitoring reverses this principle and enables proactive operations management.

IT system monitoring enables precise early detection of problems through defined thresholds that alert IT teams in good time. Automated notifications significantly reduce mean time to recovery (MTTR), as administrators can react immediately instead of waiting for error reports.

At the same time, monitoring creates data-driven transparency across the entire IT infrastructure: IT managers identify bottlenecks before they lead to performance problems and can plan resources as needed. Last but not least, IT system monitoring fulfills important compliance requirements by providing complete documentation of availability and performance for audits and certifications.

Monitoring software comparison: Icinga 2, Checkmk, and Nagios 

Choosing the right monitoring software depends on your specific requirements. Our monitoring software comparison shows that the size of the IT infrastructure, desired functionality, and available resources are decisive factors. Here, we limit ourselves to three popular open-source solutions: Icinga 2, Checkmk, and Nagios.

Unlike network monitoring tools that focus exclusively on traffic analysis and protocols, comprehensive monitoring tools keep an eye on the complete IT infrastructure. They monitor not only the network, but also servers, applications, databases, and cloud services. As a result, they offer a holistic solution for companies looking to operate their IT systems reliably and efficiently. Therefore, they cannot be described as mere network monitoring tools.

Icinga 2: Flexible monitoring with cluster features 

Icinga 2 is a powerful monitoring software with a modular architecture. The software is particularly suitable for medium-sized to large environments that require distributed monitoring setups and high availability.

Key features:

• Built-in cluster stack for high availability
• Scalability for complex multi-site infrastructures
• IDODB (Icinga Data Out Database) for advanced data evaluation
• Compatibility with external interfaces/APIs

Checkmk: Efficient monitoring with a large selection of plugins 

Checkmk impresses with an extensive plugin library and is particularly suitable for diverse, heterogeneous IT environments. The monitoring solution is used in both medium-sized businesses and large enterprises.

Highlights:

• Over 1,000 plugins for hardware, software, and cloud services
• Grafana integration for professional visualization
• HTML5 graphing system for time-series graphs
• Combination of status-, metric-, and event-based monitoring

Nagios:  The classic among monitoring software 

Nagios is a time-tested monitoring software with decades of market experience. The large community and wide range of available add-ons make Nagios a solid choice for standardized monitoring requirements.

Core features:

• Monitoring of hosts, services, and network devices
• Thousands of add-ons for specific needs
• Web interface for visualization
• Proven operational stability

CMDB and monitoring: The perfect combination 

IT system monitoring points out a problem. A Configuration Management Database (CMDB) provides the context in the form of detailed information and dependencies. This is precisely why combining the two creates real added value.

Connecting monitoring and a CMDB creates a single source of truth for the IT infrastructure. It also eliminates data silos and simplifies root cause analysis. With automatic synchronization, contextual information for alarm events, and target-vs-actual comparison, dependencies become transparent and compliance is ensured.

Monitoring integration with i-doit: Solution for IT documentation and monitoring  

 i-doit offers seamless integrations for monitoring tools such as Icinga 2, Checkmk, and Nagios. This combines IT documentation and real-time monitoring into an end-to-end solution. 

i-doit  and Icinga 2: Bidirectional coupling 

Any object with an IP or host address can be exported to Icinga 2 with a single click. There, you select the appropriate template and start monitoring.

Within Icinga 2, an icon indicates that the host originates from the i-doit CMDB and links directly back to the object's overview page. In i-doit, the current monitoring status is indicated by a colored icon on the overview page. Changes to monitored objects (e.g., a new IP address) are automatically transferred, ensuring seamless monitoring.

i-doit  add-on Checkmk 2: Target-vs-actual comparison 

The i-doit add-on Checkmk 2 seamlessly integrates the monitoring solution into the CMDB. This makes it easy to compare target data from the CMDB with actual data from monitoring:

• The Inventory Agent from Checkmk 2 provides basic information for IT documentation
• Bidirectional use of configuration data via PUSH (i-doit to Checkmk) and PULL (Checkmk to i-doit)
• Command-line tool for automated data exchange via scripts and cron jobs
• Enhanced GUI for greater visibility across the IT infrastructure

i-doit  add-on Nagios: Configuration directly from the CMDB 

The i-doit add-on Nagios connects the monitoring solution directly to the i-doit CMDB. This allows monitoring settings to be configured directly in i-doit and linked to documented objects:

• Configuration of monitoring settings directly in i-doit
• Export into valid Nagios configuration files
• Reading real-time data via NDOUtils or Livestatus
• Central management of all monitoring objects in the CMDB

Ensuring stable IT infrastructures with monitoring 

IT system monitoring has long been a basic prerequisite for stable and professionally managed IT operations. It protects against outages, supports efficient resource utilization, and provides clear transparency in complex infrastructures. Which monitoring software fits best depends on your requirements: Icinga 2 is particularly suitable for scalable, distributed environments, Checkmk impresses with broad plugin support, and Nagios remains a time-tested classic.

But monitoring alone is not enough. Only when combined with a CMDB like i-doit does it unlock its full potential: You don't just see a technical problem, you also understand the context. With the i-doit add-ons for Icinga, Checkmk, and Nagios, you create an end-to-end solution from documentation and allocation all the way to alerting.

Would you like to reliably monitor your IT infrastructure and link the retrieved data directly to a central CMDB? We would be happy to show you how i-doit can support you in the best possible way:

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