My disk is full (and it took my website or database down)

What this is#

A full disk almost never says "disk full". It says something else:

• your website is suddenly offline, throwing 500 errors or blank pages,
• MySQL/MariaDB won't start, crashes, or goes read-only, logs show Disk full (errno 28) or No space left on device,
• your app crashes whenever it writes (uploads, sessions, caches, queues),
• cron jobs, updates, even logins misbehave in strange ways.

If a service died "for no reason", check the disk before anything else. It's a ten-second test and one of the most common hidden causes of "my site/app/database is down":

df -h

If a filesystem (usually /) shows 100% (or 99%), you've found it. And if df -h shows plenty free yet writes still fail with "No space left on device", check df -i: you're likely out of inodes instead, millions of tiny files rather than big ones, which has its own guide.

Find what's eating the space#

Work down from the root, largest first:

du -xhd1 / | sort -h

Then re-run it on the biggest directory (du -xhd1 /var | sort -h, and so on) until you find the culprit. If you'd rather browse interactively, apt install ncdu and run ncdu -x /.

The usual suspects, and how to clean each safely:

• systemd journal logs. Check with journalctl --disk-usage; shrink with journalctl --vacuum-size=200M, and cap it permanently with SystemMaxUse=200M in /etc/systemd/journald.conf.
• Application and web-server logs in /var/log. An app stuck in an error loop can write gigabytes overnight. Empty a huge live log with : > /var/log/thefile.log (truncation) rather than deleting it, a deleted file that a running service still holds open keeps occupying space until the service restarts. (Find those ghosts with lsof +L1.)
• Docker. Check with docker system df. Old images, stopped containers, unused volumes, and unbounded container logs add up fast. docker system prune clears the safe stuff; add -a to also drop unused images (they'll re-download on next use). Cap container logs going forward with log rotation in /etc/docker/daemon.json.
• Package caches: apt clean (or dnf clean all).
• Old dumps and backups parked in /var/backups, /root, or your home directory, ship them off-site instead of hoarding them on the disk they're supposed to protect.

What NOT to do#

• Don't delete things you can't identify, especially anything under /var/lib (that's where your databases live, /var/lib/mysql is your data, not clutter), /usr, or /etc. Freeing space by deleting the wrong file turns an outage into data loss.
• Don't bulk-delete in /tmp on a live system without looking, running services may be mid-write there.
• Not sure what something is? Ask us, or ask an AI chatbot with the exact path, before removing it.

After you've freed space#

Restart whatever fell over, databases especially don't recover from a full disk until restarted:

systemctl restart mariadb    # or mysql, postgresql, nginx, your app...
systemctl status mariadb

Then load your site and confirm. If MySQL/MariaDB won't come back cleanly after an errno-28 incident, stop, don't experiment against your only copy of the data, follow the safe recovery order, and open a ticket with the exact log lines if it doesn't recover.

Keep it from happening again#

• Log rotation is your friend: logrotate handles /var/log by default, but confirm your app's own logs are covered, and cap journald and Docker logs as above.
• Glance at the disk graph on your VPS's Graphs tab now and then, disk usage grows slowly and visibly; catching it at 85% is painless.
• Genuinely need more room? Additional Storage adds disk without changing your plan, or upgrade if everything is getting tight.

Related questions#

• "My website suddenly went down, could the disk be full?"
• "MySQL won't start and says disk full (errno 28), what do I do?"
• "How do I find what's using all my disk space?"
• "Is it safe to delete Docker images or journal logs?"
• "Why does it say no space left when the disk isn't full (inodes)?"
• "How do I add more disk space to my VPS?"