IBM AIX 7.2 – Common Problem 123 – 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

vmstat shows fre near zero and applications experience long pauses.

Environment & Reproduction

AIX 7.2 LPAR with default VMM tunables and heavy file cache pressure.

Root Cause Analysis

minfree/maxfree set too low for the workload’s allocation bursts.

Quick Triage

Run vmstat 2 5 and svmon -G to view free pages and pinned memory.

Step-by-Step Diagnosis

Capture vmo -L to see current minfree, maxfree and maxperm settings.

Solution – Primary Fix

Raise minfree/maxfree with vmo -p -o minfree=1024 -o maxfree=2048.

Solution – Alternative Approaches

Tune maxperm%/maxclient% with vmo to limit file cache growth.

Verification & Acceptance Criteria

vmstat fre stays above minfree and run-queue length normalizes.

Rollback Plan

Revert vmo settings with vmo -d minfree -d maxfree if regressions occur.

Prevention & Hardening

Capture vmo -L baselines per workload and review after every upgrade.

Related Errors & Cross-Refs

Pairs with PGSP_KILL and process termination errpt entries.

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: vmo, VMM tuning concepts on AIX 7.2.