Ubuntu 20.04 LTS – Common Problem 009 – Diagnosis and Fix

📖 ~1 min read

Table of contents

1. Symptom & Impact
2. Environment & Reproduction
3. Root Cause Analysis
4. Quick Triage
5. Step-by-Step Diagnosis
6. Solution – Primary Fix
7. Solution – Alternative Approaches
8. Verification & Acceptance Criteria
9. Rollback Plan
10. Prevention & Hardening
11. Related Errors & Cross-Refs
12. References & Further Reading

Symptom & Impact

Root filesystem reaches 100%, causing apt failures, service crashes, and inability to write temp files.

Environment & Reproduction

Ubuntu 20.04 server with verbose services and default journald retention on small volumes.

Root Cause Analysis

Unbounded logs, old crash dumps, and unattended cache accumulation consume critical disk space.

Quick Triage

Use ‘df -h’, ‘sudo du -xhd1 /var’, and ‘journalctl –disk-usage’ to locate top consumers fast.

Step-by-Step Diagnosis

Trace growth paths under ‘/var/log’, ‘/var/lib/snapd’, and apt cache; review rate of new log writes.

Solution – Primary Fix

Vacuum journals with ‘sudo journalctl –vacuum-time=7d’, clear apt cache, and rotate oversized logs.

Solution – Alternative Approaches

Move logs to separate volume, enable remote logging, or expand disk/LVM capacity.

Verification & Acceptance Criteria

Free space exceeds operational threshold and growth rate returns to expected baseline.

Rollback Plan

Restore archived logs if forensic retention is required and accidental deletion occurred.

Prevention & Hardening

Set journald size limits, configure logrotate aggressively, and alert before disk critical levels.

Related Errors & Cross-Refs

No space left on device, apt unable to write lists, and systemd service restart loops.

Related tutorial: View the step-by-step tutorial for Ubuntu 20.04 LTS.

View all Ubuntu 20.04 LTS tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

journald.conf man page, logrotate docs, and Ubuntu storage operations guidance.