What is server monitoring?
What Gets Monitored
Server monitoring tracks key resources: CPU usage, memory consumption, disk space, disk I/O, network traffic, and running processes. It also checks service availability, like whether a web server responds.
Beyond raw metrics, monitoring often includes log aggregation and alerting. Tools like Prometheus, Nagios, Zabbix, and Datadog collect and visualize this data.
- CPU load and utilization
- Memory and swap usage
- Disk space and I/O
- Network latency and throughput
- Service uptime and response time
Why It's Important
Monitoring helps you spot problems before they cause outages. For example, a gradual increase in memory usage might indicate a memory leak that will eventually crash the server.
It also provides data for capacity planning and performance tuning. Without monitoring, you're flying blind and only learn about issues when users complain.
Types of Monitoring
There are two main approaches: agent-based (install software on the server) and agentless (use protocols like SNMP or SSH). Both have trade-offs in ease of setup and depth of data.
Modern monitoring often includes alerting rules that notify via email, Slack, or PagerDuty when thresholds are crossed.
- Agent-based: more detailed metrics
- Agentless: simpler, no install
- Alerting: threshold-based or anomaly detection
- Dashboards: visualize trends over time
Common mistakes
- Monitoring only uptime and ignoring resource trends.
- Setting alerts too sensitive, causing alert fatigue.
- Forgetting to monitor disk space, which often fills up silently.
