Skip to main content

Disk Management: Don't Run Out of Space

Running out of disk space breaks things. Services stop. Systems crash. Data is lost.

Here's the thing: Monitor disk space. Always. Running out is bad.

df: How Much Space Do You Have?​

df -h                             # Human-readable
df -h /                           # Specific filesystem
df -i                             # Inode usage

What it shows: Disk space usage for filesystems.

Real example:

$ df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/sda1        20G   15G  4.0G  79% /
/dev/sda2       100G   45G   50G  48% /home

What matters: The Use% column. Above 80% is warning. Above 90% is critical.

My take: Check df -h regularly. Know your disk usage. Prevent problems.

du: What's Using Space?​

du -h                             # Current directory
du -sh                            # Summary (total)
du -h --max-depth=1 .              # One level deep
du -h *                            # Each item

What it shows: Disk usage for files and directories.

Real example:

$ du -sh *
2.1G    projects
500M    downloads
100M    documents

My take: Use du -sh * to see what's using space. Find the big stuff.

Finding Large Files​

find / -type f -size +100M         # Files larger than 100MB
find / -type f -size +1G           # Files larger than 1GB
find / -type f -exec du -h {} \; | sort -rh | head -10  # Top 10 largest

Real example:

$ find /var/log -type f -size +100M
/var/log/syslog.1
/var/log/nginx/access.log

My take: Find large files. Delete old logs. Free up space.

Common Space Hogs​

Log Files​

du -sh /var/log
find /var/log -type f -size +100M

My take: Logs grow. They consume space. Rotate them. Delete old ones.

Temporary Files​

du -sh /tmp
du -sh /var/tmp

My take: Temp files accumulate. Clean them. They're temporary for a reason.

Package Cache​

du -sh /var/cache/apt
sudo apt clean                     # Clean package cache

My take: Package cache grows. Clean it. apt clean frees space.

Cleaning Up​

Log Rotation​

sudo logrotate -f /etc/logrotate.conf

My take: Logs should rotate automatically. Check if it's working.

Remove Old Logs​

find /var/log -type f -mtime +30 -delete

My take: Delete logs older than 30 days. Adjust as needed.

Clean Package Cache​

sudo apt clean                     # Debian/Ubuntu
sudo dnf clean all                 # RHEL/CentOS

My take: Clean package cache regularly. Frees space.

Remove Old Kernels​

sudo apt autoremove                # Debian/Ubuntu

My take: Old kernels accumulate. Remove them. autoremove does it.

Monitoring Disk Usage​

Check Regularly​

df -h                             # Quick check

My take: Make it a habit. Check disk space. Prevent problems.

Set Up Alerts​

# Script to check and alert
if [ $(df -h / | awk 'NR==2 {print $5}' | sed 's/%//') -gt 80 ]; then
    echo "Warning: Disk usage above 80%"
fi

My take: Automate monitoring. Get alerts before it's critical.

Common Mistakes (I've Made These)​

  1. Not monitoring: Disk fills up. System breaks. Monitor it.

  2. Ignoring warnings: 80% is warning. 90% is critical. Don't ignore.

  3. Not cleaning logs: Logs grow. They consume space. Rotate them.

  4. Deleting wrong files: Be careful. Don't delete system files.

  5. Not checking regularly: Check disk space. Make it a habit.

Real-World Examples​

Check Disk Space​

df -h

Find Large Files​

find / -type f -size +1G 2>/dev/null

Clean Logs​

sudo find /var/log -type f -mtime +30 -delete

Free Up Space​

sudo apt clean
sudo apt autoremove
sudo find /tmp -type f -mtime +7 -delete

What's Next?​

Now that you can monitor disk usage, you can prevent problems. Or learn about Storage Management for advanced storage.

Personal note: I've had systems crash because disk filled up. Services stopped. Logs couldn't write. It was a mess. Now I monitor disk space. I clean logs. I prevent problems. Monitor disk space. It matters.