IBM AIX 7.3 – Common Problem 113 – 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 reports high %pi indicating heavy paging from disk.

Environment & Reproduction

Memory pressure from large processes or shrinking lruable RAM.

Root Cause Analysis

VMM is paging in cold pages faster than it can reclaim.

Quick Triage

Open topas -M and watch PgSp In/Out columns.

Step-by-Step Diagnosis

Use svmon -G and -P -O sortseg=pgsp -r to find big users.

Solution – Primary Fix

Tune lru_file_repage=0 and maxperm%=90 with vmo -p.

Solution – Alternative Approaches

Add RAM via DLPAR or move workload to bigger LPAR.

Verification & Acceptance Criteria

topas %pi drops to near zero under load.

Rollback Plan

Revert vmo with vmo -d to defaults if regressed.

Prevention & Hardening

Set up nmon collection to baseline page activity.

Related Errors & Cross-Refs

Pairs with paging-space-exhaustion when sustained.

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 Docs: vmo, svmon, topas.