Ubuntu 18.04 LTS – Common Problem 007 – 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

Disk usage rises quickly and /var/log consumes significant space, impacting services.

Environment & Reproduction

Ubuntu 18.04 servers with verbose logging or repeated service failures feeding journald.

Root Cause Analysis

journald retention defaults and noisy logs lead to unbounded growth without explicit size limits.

Quick Triage

Use journalctl –disk-usage and du -sh /var/log/journal to quantify immediate impact.

Step-by-Step Diagnosis

Identify chatty units via journalctl -p warning..alert and repeated stack traces with specific unit filters.

Solution – Primary Fix

Run journalctl –vacuum-time=7d or –vacuum-size=500M, then set SystemMaxUse in /etc/systemd/journald.conf and restart journald.

Solution – Alternative Approaches

Forward logs to external collectors and reduce local persistence where compliance permits.

Verification & Acceptance Criteria

Disk usage drops to target threshold and log growth remains bounded over subsequent days.

Rollback Plan

Restore previous journald.conf and restart journald if retention changes affect audit requirements.

Prevention & Hardening

Set explicit retention policy and monitor log volume spikes via alerts.

Related Errors & Cross-Refs

No space left on device, failed writes to /var/log, and service restart loops.

Related tutorial: View the step-by-step tutorial for Ubuntu 18.04 LTS.

View all Ubuntu 18.04 LTS tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

man journald.conf, man journalctl, and Ubuntu logging best practices.