IBM AIX 7.2 – Common Problem 007 – 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

topas shows 100% CPU in a WPAR while LPAR caps starve other workloads.

Environment & Reproduction

IBM AIX 7.2 LPAR exhibiting CPU saturation / WPAR issues under standard PowerVM workloads.

topas -P
lparstat 2 5

Root Cause Analysis

Runaway process or WPAR resource set exceeds entitlement.

Quick Triage

Confirm scope with errpt, recent changes, and subsystem state via lssrc.

ps aux | sort -k3 -r | head
lssrc -s wparexec

Step-by-Step Diagnosis

Profile the offending process inside the WPAR with proctree and tprof.

tprof -x sleep 30
proctree 

Solution – Primary Fix

Apply WPAR resource controls or raise LPAR entitled capacity.

chwpar -R shares_CPU=200 wpar1
chhwres -m sys1 -r proc -o a --procs 1

Solution – Alternative Approaches

Cap process with renice and project-level resource sets via WLM.

Verification & Acceptance Criteria

Confirm subsystem returns to RUNNING state and errpt shows no new entries.

lparstat 2 5
topas -P | head

Rollback Plan

Restore prior configuration from mksysb or alt_disk_install clone if the fix regresses.

chwpar -R shares_CPU=100 wpar1

Prevention & Hardening

Encode the fix in NIM customisation scripts and monitor via topas/nmon.

smit wlm  # define class with cpu share limits

Related Errors & Cross-Refs

errpt CPU_OVERFLOW; tprof high kernel time

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

AIX Workload Partitions Best Practices