Auditd Backlog Overflow and Lost Audit Events

📖 ~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

Security logs report lost audit events and backlog overflow messages.

Environment & Reproduction

Audit event rate exceeds current kernel backlog and userspace processing throughput.

Root Cause Analysis

Run: sudo auditctl -s and inspect journalctl -u auditd for overflow alerts.

Quick Triage

Review noisy audit rules and verify disk I/O is not throttling audit log writes.

Step-by-Step Diagnosis

Capture kernel/auditd messages that show dropped records.

Solution – Primary Fix

Capture improved status after backlog and rule tuning.

Solution – Alternative Approaches

Increase backlog in /etc/default/grub (audit_backlog_limit=8192) and rebuild grub config.

Verification & Acceptance Criteria

Tune auditd.conf flush/freq and reduce high-volume nonessential rules.

Rollback Plan

Restart auditd if policy permits and monitor event throughput.

Prevention & Hardening

Confirm auditctl -s shows healthy backlog and no new lost-event warnings.

Related Errors & Cross-Refs

Benchmark audit rule sets per host role and document supported event rates.

Related tutorial: View the step-by-step tutorial for rhel-9.

View all rhel-9 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Restore prior audit tuning if increased backlog causes undesired memory use.