Debian 11: PostgreSQL fails because WAL partition is full

📖 ~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

PostgreSQL cannot continue writes because WAL storage reaches capacity.

Environment & Reproduction

Applications fail on write transactions and logs report no space left in pg_wal.

Root Cause Analysis

Check usage with `df -h`, review WAL directory size, and inspect PostgreSQL logs for archiving backlog.

Quick Triage

Archiving misconfiguration, replication lag, or long transactions prevent WAL recycling.

Step-by-Step Diagnosis

Restore free space safely, resolve archiving or replication blockers, and tune retention parameters.

Solution – Primary Fix

Confirm WAL size stabilizes, archiver status is healthy, and writes succeed under load.

Solution – Alternative Approaches

Set capacity alerts on WAL volume and test archive pipelines regularly.

Verification & Acceptance Criteria

Revert parameter changes if they increase risk, while preserving safe archive guarantees.

Rollback Plan

Automate checks for archive_command success and replication slot growth.

Prevention & Hardening

`df -h`; `du -sh /var/lib/postgresql/*/main/pg_wal`; `sudo -u postgres psql -c ‘select now();’`

Related Errors & Cross-Refs

Include archive logs, slot status, and transaction age metrics for database response teams.

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

Manual WAL deletion is unsafe and can make recovery impossible without valid backups.