IBM AIX 7.2 – Common Problem 125 – 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

HMC reports ‘DLPAR operation failed’ when adding CPU to an AIX 7.2 LPAR.

Environment & Reproduction

Profile maximum not large enough or RMC inactive on the LPAR.

Root Cause Analysis

HMC cannot communicate with the LPAR or hits the configured max processors.

Quick Triage

Verify RMC is Active in HMC and lparstat -i on the LPAR.

Step-by-Step Diagnosis

Compare current/min/max processors in the LPAR profile with the target.

Solution – Primary Fix

Increase max procs in the LPAR profile and reactivate or restart RMC.

Solution – Alternative Approaches

Restart RMC with rmcctrl -p on the LPAR if HMC shows Inactive.

Verification & Acceptance Criteria

HMC DLPAR add succeeds and lparstat -i reflects the new processor count.

Rollback Plan

Roll back to the previous profile if the LPAR misbehaves after the change.

Prevention & Hardening

Pre-size profile maximums for growth and monitor RMC health.

Related Errors & Cross-Refs

Pairs with errpt RMC_DAEMON or hcnfsd notices.

Related tutorial: View the step-by-step tutorial for aix-7.2.

View all aix-7.2 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

IBM Docs: HMC DLPAR operations, RSCT/RMC requirements.