Understanding VPS Resources - RAM, CPU, storage, bandwidth limits and monitoring

Your Node.js app died overnight because it ate all 4GB of RAM on your $3.99 Hetzner server. Your database is crawling because you’re swapping to disk. You just discovered you’re burning through your 20TB bandwidth faster than expected.

You have no idea what “normal” resource usage looks like, so you’re flying blind until something breaks.

Let’s learn how to monitor your VPS resources correctly so that you can first of all see what’s going wrong and ensure it doesn’t happen again.

Essential Monitoring Commands

Check Current Resource Usage

# Quick overview - shows live CPU, memory, disk usage
htop

# Memory usage breakdown
free -h

# Disk space usage
df -h

# CPU usage over time (5 second intervals)
iostat 5

# Network bandwidth usage
iftop -i eth0

Find Resource Hogs

# Top processes by memory usage
ps aux --sort=-%mem | head -10

# Top processes by CPU usage
ps aux --sort=-%cpu | head -10

# Find large files eating disk space
du -h / | sort -hr | head -20

# Check which process is using bandwidth
ss -tuln | grep :80  # Check what's listening on port 80

Historical Resource Usage

# System load average (1, 5, 15 minutes)
uptime

# Memory usage trend
vmstat 1 5  # Shows 5 samples, 1 second apart

# Disk I/O statistics
iostat -x 1 5

# Check bandwidth usage this month
vnstat -m

💡

Load Average Reality Check

On a 1 vCPU system, load average above 1.0 means you’re overloaded. On a 4 vCPU system, above 4.0 is trouble.

Setting Up Basic Monitoring

Install Essential Tools

# Install tools
sudo apt install htop iotop vnstat -y
sudo systemctl enable --now vnstat

Quick Alert Script

# Create /opt/scripts/check-resources.sh
#!/bin/bash
MEM=$(free | awk '/^Mem:/{printf("%.0f"), $3/$2*100}')
DISK=$(df / | awk 'NR==2{gsub(/%/,""); print $5}')
LOAD=$(uptime | awk -F'load average:' '{print $2}' | cut -d',' -f1 | tr -d ' ')

[ $MEM -gt 80 ] && echo "ALERT: Memory ${MEM}%" && ps aux --sort=-%mem | head -3
[ $DISK -gt 85 ] && echo "ALERT: Disk ${DISK}%" && du -sh /var/log
[ $(echo "$LOAD > 1.5" | bc) -eq 1 ] && echo "ALERT: Load $LOAD" && ps aux --sort=-%cpu | head -3

sudo chmod +x /opt/scripts/check-resources.sh

# Run every 10 minutes
echo "*/10 * * * * /opt/scripts/check-resources.sh" | sudo crontab -

Simple Resource Dashboard

# Create a quick status command
echo 'alias status="echo \"=== SYSTEM STATUS ===\"; uptime; echo; free -h; echo; df -h /; echo; ps aux --sort=-%mem | head -5"' >> ~/.bashrc

source ~/.bashrc

# Run it anytime
status

Warning Signs Before Things Break

Memory Problems

# Swap usage indicates RAM pressure
free -h | grep Swap

# Out of Memory Killer logs
dmesg | grep -i "killed process"
# If you see this, processes are being killed due to low memory

CPU Issues

# Load average consistently above number of vCPUs
uptime

# High CPU wait (wa) indicates I/O bottleneck
iostat 1 1
# If %wa is consistently above 20%, you have disk I/O problems

Disk Problems

# Less than 10% free space = trouble incoming
df -h /

# High disk I/O wait times
iostat -x 1 5
# If await > 100ms consistently, your disk is struggling

Network Issues

# Bandwidth usage this month
vnstat -m
# If you're approaching your monthly limit

# Check for DDoS or unusual traffic patterns
ss -tuln | wc -l  # Count active connections
netstat -ntu | awk '{print $5}' | cut -d: -f1 | sort | uniq -c | sort -n

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When to Upgrade vs Optimize

Quick Optimizations

Memory issues on 4GB:

Add 2GB swap: sudo fallocate -l 2G /swapfile && sudo chmod 600 /swapfile && sudo mkswap /swapfile && sudo swapon /swapfile
Disable snapd: sudo systemctl disable snapd.service (saves 50-100MB)

Upgrade when:

Swap usage constant
Load consistently > 2.0 on 2 vCPU
Memory constantly > 80%

CAX11 ($3.99) → CAX21 ($6.99): Double everything (4 vCPU, 8GB RAM, 80GB storage)

What Could Go Wrong

Can’t SSH due to high load: Use your provider’s console and sudo reboot

Emergency cleanup:

# Free disk space
sudo apt autoremove -y && sudo journalctl --vacuum-time=7d

# Kill runaway processes
sudo pkill -f process-name

Reality Check

20 minutes setup saves hours of debugging at night. CAX11 ($3.99) handles a lot with 4GB RAM and ARM efficiency. Upgrade to CAX21 when you consistently hit 80% on any resource.