Monitoring Server Resources: CPU, Memory, and Disk

Effective server monitoring helps you detect issues before they cause downtime. Learn how to monitor your Linux server resources.

Why Monitor Server Resources?

Resource monitoring helps you:

• Detect performance bottlenecks
• Prevent outages from resource exhaustion
• Optimize application performance
• Plan for scaling needs
• Troubleshoot issues quickly

Quick Resource Overview Commands

Check CPU Usage

top
# or
htop  # More user-friendly (install with: sudo apt install htop)

Check Memory Usage

free -h

Check Disk Usage

df -h

Check Disk I/O

iostat
# Install with: sudo apt install sysstat

Detailed Monitoring with top/htop

Understanding top Output

top - 14:30:42 up 10 days,  3:21,  1 user,  load average: 0.52, 0.58, 0.59
Tasks: 123 total,   1 running, 122 sleeping
%Cpu(s):  2.3 us,  0.7 sy,  0.0 ni, 96.7 id,  0.3 wa
MiB Mem :   3951.4 total,    245.8 free,   2341.5 used,   1364.1 buff/cache

Key metrics:

• load average: System load (should be below CPU core count)
• us (user): CPU time on user processes
• sy (system): CPU time on system processes
• id (idle): CPU idle time
• wa (wait): CPU waiting for I/O

Using htop Effectively

Install htop:

sudo apt install htop

Key features:

• Color-coded CPU and memory bars
• Tree view of processes (F5)
• Search processes (F3)
• Kill processes (F9)
• Sort by various metrics (F6)

Memory Monitoring

Check Memory Details

free -h

Output:

total        used        free      shared  buff/cache   available
Mem:          3.9Gi       2.3Gi       240Mi        10Mi       1.3Gi       1.4Gi
Swap:         2.0Gi       512Mi       1.5Gi

• total: Total physical RAM
• used: RAM used by processes
• free: Unused RAM
• buff/cache: RAM used for caching (can be freed if needed)
• available: RAM available for new applications

Find Memory-Hungry Processes

ps aux --sort=-%mem | head

Disk Monitoring

Check Disk Space

df -h

Find Large Files

du -h --max-depth=1 | sort -hr | head -20

Find Large Files Recursively

find / -type f -size +100M -exec ls -lh {} \; 2>/dev/null

Monitor Disk I/O in Real-Time

iostat -x 2

Setting Up Alerts

Email Alert for High CPU

Create /usr/local/bin/cpu-alert.sh:

#!/bin/bash
CPU_THRESHOLD=80
CPU_USAGE=$(top -bn1 | grep "Cpu(s)" | sed "s/.*, *\([0-9.]*\)%* id.*/\1/" | awk '{print 100 - $1}')

if (( $(echo "$CPU_USAGE > $CPU_THRESHOLD" | bc -l) )); then
    echo "High CPU usage: $CPU_USAGE%" | mail -s "CPU Alert" admin@example.com
fi

Add to crontab:

*/5 * * * * /usr/local/bin/cpu-alert.sh

Using Monitoring Tools

Install netdata (Real-time Monitoring)

bash <(curl -Ss https://my-netdata.io/kickstart.sh)

Access at: http://your-server-ip:19999

Best Practices

1. Monitor Trends: Track metrics over time, not just snapshots
2. Set Alerts: Get notified before problems become critical
3. Regular Reviews: Check metrics weekly
4. Document Baselines: Know your normal resource usage
5. Capacity Planning: Monitor growth trends for scaling decisions

Conclusion

Regular resource monitoring prevents performance issues and downtime. Gumpbox provides beautiful, real-time visualizations of your server resources in an easy-to-use dashboard.

Next Steps

• Automating Linux server Backups with Cron Jobs
• Optimizing MySQL Performance on Your Linux server