🟠 High   ⏱ 5–30 min  Last verified: 19 May 2026
Affected versions: Debian 11

📖 ~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 service failures, write errors, and possible database disruption.

Environment & Reproduction

Common on verbose services with persistent journals and no retention limits in long-running hosts.

Root Cause Analysis

systemd-journald defaults can consume large space when rate-limited events are absent and cleanup is not enforced.

Quick Triage

Run df -h and journalctl –disk-usage, then identify whether journald dominates /var usage.

Step-by-Step Diagnosis

Use du -xh /var | sort -h, journalctl –vacuum-time=1s –dry-run equivalent checks, and inspect /etc/systemd/journald.conf.

Illustrative mockup for debian-11 — terminal_or_shell
Disk usage commands identifying journal growth — Illustrative mockup — Progressive Robot

Solution – Primary Fix

Apply SystemMaxUse and RuntimeMaxUse limits, restart systemd-journald, and vacuum old logs with journalctl –vacuum-size=1G.

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Illustrative mockup for debian-11 — log_or_config
journald retention settings applied for persistent control — Illustrative mockup — Progressive Robot

Solution – Alternative Approaches

Forward logs to central syslog stack or mount /var/log on dedicated storage with rotation policy.

Verification & Acceptance Criteria

Disk usage must return below operational threshold and log ingestion should continue without service interruption.

Rollback Plan

Revert journald.conf from backup and restore archived journals if compliance needs historical data restoration.

Prevention & Hardening

Set alerting at 75% disk use, enforce log budgets per service, and test retention in staging.

Look for “No space left on device” and application write failures tied to /var exhaustion.

Related tutorial: View the step-by-step tutorial for debian-11.

View all debian-11 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Refer to systemd-journald manual and Debian logging best-practice guides.

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