IBM AIX 7.3 – Common Problem 004 – 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

Workload latency rises and lparstat shows 100% physc utilization with high ec consumption.

Environment & Reproduction

IBM AIX 7.3 LPAR exhibiting CPU saturation / lparstat issues under standard PowerVM workloads.

lparstat 2 5
mpstat 2 5

Root Cause Analysis

Under-provisioned entitled capacity or runaway threads consume all available processor units.

Quick Triage

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

topas -P
ps aux | sort -rk3 | head

Step-by-Step Diagnosis

Profile per-LPAR CPU and check shared pool contention.

lparstat -i
mpstat -s 2 5

Solution – Primary Fix

Increase entitled capacity via DLPAR or cap the offending process.

chhwres -r proc -m frame -o a -p lpar1 --procunits 0.5

Solution – Alternative Approaches

Move workload to a dedicated LPAR or adjust SMT mode.

Verification & Acceptance Criteria

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

lparstat 1 3
smtctl

Rollback Plan

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

chhwres -r proc -m frame -o r -p lpar1 --procunits 0.5

Prevention & Hardening

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

smtctl -t 4  # tune SMT and weight

Related Errors & Cross-Refs

errpt LABEL=SCHED_HOG; high run queue

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 Power Systems performance tuning guide