How to Fix a Full Root Partition on Linux

What Causes This?

A full Linux root partition usually happens when system logs, package caches, old kernels, temporary files, or leftover app data keep growing until the / partition runs out of space. It can also happen after failed updates, large Docker or Snap files, or when a small root partition was created during installation. Once the root partition is full, Linux may stop writing important system files and start failing in unpredictable ways.

Common Symptoms

• You see “No space left on device” errors
• Apps fail to open, install, or update
• Linux updates stop partway through or report package errors
• The system becomes unstable, slow, or won’t boot properly
• Logins fail or the desktop loads with missing features

How to Fix It Manually

1. Check whether the root partition is actually full

   • Open a terminal.
   • Run:

     df -h /

   • Look at the Use% column. If it is near or at 100%, your root partition is full.

2. Find which directories are using the most space

   • In the terminal, run:

     sudo du -xhd1 / | sort -h

   • This shows the largest top-level folders on the root partition only.
   • If /var, /usr, /home, or /tmp is unusually large, check inside it with a command like:

     sudo du -xhd1 /var | sort -h

3. Clear package manager caches

   • On Debian, Ubuntu, or Linux Mint, run:

     sudo apt clean

   • Then remove unused packages:

     sudo apt autoremove --purge

   • On Fedora:

     sudo dnf clean all

   • On Arch:

     sudo pacman -Scc

   • This often frees several GB safely.

4. Clean old logs and temporary files

   • Check journal log size:

     journalctl --disk-usage

   • Reduce it to a reasonable size:

     sudo journalctl --vacuum-size=200M

   • Remove old temp files:

     sudo rm -rf /tmp/*

   • Be careful not to delete files from system folders unless you know what they are.

5. Remove old kernels, Snap packages, or Docker data

   • On Ubuntu-based systems, old kernels are often removed by:

     sudo apt autoremove --purge

   • To check Snap usage:

     snap list --all

   • Docker can also consume large amounts of space:

     docker system df
     docker system prune

   • Only remove Docker data if you understand what containers and images you still need.

6. Look for oversized files

   • Run:

     sudo find / -xdev -type f -size +500M 2>/dev/null

   • This lists files larger than 500 MB on the root partition.
   • Review the results carefully before deleting anything. Large log files, installer leftovers, VM images, and backups are common causes.

7. Reboot and confirm free space

   • Restart the system:

     sudo reboot

   • After logging back in, run:

     df -h /

   • Make sure you now have enough free space for updates and normal system use.

Fix It Automatically with Kudu

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