Table of Contents

• Why Monitoring Matters
• What to Monitor (Key Performance Metrics)
  • 1. CPU Usage
  • 2. Memory Usage
  • 3. Disk I/O and Storage
  • 4. Network Usage
  • 5. Processes and Services
  • 6. System Logs
• Tools to Automate Monitoring
• Best Practices
• Conclusion
• Let's Connect on LinkedIn

Why Monitoring Matters

You’ve updated your systems. Applied patches. Everything seems fine.

But no system can be truly secure or efficient without ongoing monitoring.

Lack of Monitoring Leads to Vulnerability:

• No logs = No alerts = delayed response to attacks or resource exhaustion
• No visibility means attackers could go unnoticed (e.g., unauthorized SSH access)
• Unpatched systems or performance spikes might indicate compromise but without monitoring, you'd never know.

Cybercriminals thrive in the dark. Monitoring shines a light.

In a production environment, a slow server is more dangerous than a down server.

Because it appears to be working until users start complaining.

That’s where system performance monitoring comes in.

Linux monitoring acts as your early warning system, ensuring the system is:

• Available (users and applications can access it)
• Responsive (no slowdowns or timeouts)
• Efficient (resources are used properly)
• Stable (no unexpected crashes or overloads)

What to Monitor (Key Performance Metrics)

1. CPU Usage

Tracks how much processor time is being used.

High usage may indicate heavy processes or a bottleneck.

Tools: top, htop, mpstat, sar

2. Memory Usage

Includes RAM and swap usage.

Consistently high memory could lead to thrashing.

Tools: free -m, vmstat, top, smem

3. Disk I/O and Storage

Monitors how fast and frequently the disk is being read/written to.

Disk bottlenecks can affect database performance, logging, backups, etc.

Tools: iostat, iotop, df -h, du, lsblk

4. Network Usage

Measures traffic in/out, bandwidth usage, and errors.

Helps detect congestion, packet loss, or DDoS attacks.

Tools: iftop, nethogs, netstat, ss, ping, traceroute

5. Processes and Services

Ensures critical services are running and performing as expected.

Tracks resource-hungry or zombie processes.

Tools: ps aux, systemctl status, top, journalctl

6. System Logs

Check logs for warnings, errors, failed authentications.

Location:

/var/log/, /var/log/messages, /var/log/syslog, /var/log/auth.log

Tools: tail -f, grep, journalctl

Tools to Automate Monitoring

• Glances : real-time overview
• Zabbix : graphs, alerts, dashboard
• Netdata : intuitive web UI
• Nagios : powerful alert system
• Prometheus + Grafana : modern dashboards and metrics

While tools are essential, monitoring is not just about tools.

It’s about:

• Setting performance thresholds
• Understanding baselines
• Creating alert systems
• Interpreting logs and metrics to make informed decisions

Best Practices

• Set alerts for CPU, memory, disk, and network
• Establish baseline performance
• Monitor trends to scale resources ahead
• Combine command-line tools with automated platforms

Conclusion

Monitoring = Tools + Skills + Logs + Baselines + Action Plan

System monitoring is a preventive shield, a performance enhancer, and your early warning system.

You don’t need to wait until there's a problem.

Start watching now before someone else is watching for you.

Let’s connect on LinkedIn

(https://www.linkedin.com/in/chiamaka-chielo?utm_source=share&utm_campaign=share_via&utm_content=profile&utm_medium=android_app)

As I automate my journey into RHCE and Ansible, I’d love to connect with fellow learners and professionals. Feel free to reach out and join me as I share tips, resources, and insights throughout this 30-day challenge.

cloudwhistler #30daysLinuxchallenge