A short checklist for the disk-full page

Written after doing these in the wrong order once too often.

1. df -h and df -i. Space and inodes fail differently.
2. du -xh --max-depth=2 / | sort -h | tail. Stay on one filesystem with -x.
3. Deleted but open files: lsof +L1. Restart the holder, do not hunt the file.
4. Journal size: journalctl --disk-usage, then set SystemMaxUse.
5. Container logs and dangling images.
6. Package caches.

Afterwards

Add an alert at 80 percent. The fix is never as interesting as learning why nothing warned you.