📖 ~1 min read
Table of contents
Symptom & Impact
Cluster resources stop or relocate unpredictably because fencing requests fail or time out.
Environment & Reproduction
In RHEL 8 HA clusters, node fault tests trigger unsuccessful STONITH operations.
Root Cause Analysis
Invalid agent credentials, unreachable fence device, or too-short timeout values cause incomplete fencing.
Quick Triage
Use pcs status, journalctl -u pacemaker, and fence agent debug tests to identify failing stage.
Step-by-Step Diagnosis
Validate network reachability to fence endpoints, confirm credentials, and review fencing topology configuration.
Solution – Primary Fix
Update STONITH device parameters and timeout values, then retest fencing and recover cluster resources.
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Solution – Alternative Approaches
Introduce redundant fencing paths or alternate agents supported by the hardware platform.
Verification & Acceptance Criteria
Manual fence tests succeed, quorum remains stable, and failover scenarios complete predictably.
Rollback Plan
Revert to previous pcs configuration backup and restore prior validated fencing definitions.
Prevention & Hardening
Schedule regular fence validation drills and monitor pacemaker event logs for early drift indicators.
Related Errors & Cross-Refs
Commonly connected to DNS resolution issues, management network ACL changes, and certificate expiry.
Related tutorial: View the step-by-step tutorial for rhel-8.
View all rhel-8 tutorials on the Tutorials Hub →
Browse all common problems & solutions on the Tutorials Hub.
References & Further Reading
Consult Red Hat High Availability and Pacemaker fencing best-practice documentation for RHEL 8.
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