IBM AIX 7.3 – Common Problem 121 – 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

VIO SEA flaps between primary and backup repeatedly.

Environment & Reproduction

Shared Ethernet Adapter health check misconfigured or VLAN drift.

Root Cause Analysis

ha_mode and ctl_chan miswired after VIOS upgrade.

Quick Triage

Run entstat -all entN | grep -E ‘Primary|Backup’ on both VIOS.

Step-by-Step Diagnosis

Inspect chdev attrs ha_mode, ctl_chan, jumbo_frames consistency.

Solution – Primary Fix

Set ha_mode=sharing and matching ctl_chan VLAN on both VIOS.

Solution – Alternative Approaches

Force primary with chdev -l entN -a ha_mode=standby on backup.

Verification & Acceptance Criteria

entstat ‘Failover’ counter stays 0 for 24h.

Rollback Plan

Revert to single SEA temporarily if storm persists.

Prevention & Hardening

Document SEA VLAN/PVID matrix per VIO Server pair.

Related Errors & Cross-Refs

Pairs with EtherChannel mode mismatches.

Related tutorial: View the step-by-step tutorial for aix-7.3.

View all aix-7.3 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

IBM Docs: SEA, VIOS networking.