IBM AIX 7.3 – Common Problem 240 – 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 Runq stays > vCPU count and load average is sustained high.

Environment & Reproduction

Seen during batch windows or after a runaway process spawns many threads.

Root Cause Analysis

More runnable threads than available virtual CPUs; scheduler queue grows.

Quick Triage

Run topas -P or ps -ekf | sort -rk 4 | head to find heavy threaded processes.

Step-by-Step Diagnosis

Use nmon -fT then nmon analyzer or mpstat to confirm sustained queue depth.

Solution – Primary Fix

Renice or contain the offending process and add CPU entitlement via DLPAR.

Solution – Alternative Approaches

Move the workload to a dedicated LPAR or split across more LPARs.

Verification & Acceptance Criteria

topas Runq returns near vCPU count and application latency normalizes.

Rollback Plan

Roll back DLPAR additions once the burst window closes if capacity is constrained.

Prevention & Hardening

Use WLM or PowerVM partition profiles to throttle batch jobs.

Related Errors & Cross-Refs

May trigger paging-space-low if memory pressure follows.

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 AIX 7.3 Performance Management – topas and runq guidance.