IBM AIX 7.1 – Common Problem 172 – 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

LPAR memory total drops unexpectedly. AIX reports less memory than HMC provisioned, hinting at a DIMM guard event.

Environment & Reproduction

Affects Power frames where ECC reports persistent correctable errors.

lparstat -i | grep Memory
oslevel -s
uname -a

Root Cause Analysis

Cause is service processor deconfiguring a DIMM after correctable-error threshold, removing capacity from partitions.

Quick Triage

Confirm memory counts and event history.

lparstat -i | grep Memory

Step-by-Step Diagnosis

Capture deeper evidence to isolate the failure path.

lparstat -i | grep Memory
lscfg -vp | grep -i memory | head
errpt -a -j 35BFC499 | head
lsmcode -A
prtconf | head -n 40

Solution – Primary Fix

Apply the proven primary fix in a controlled change window.

diag
lsmcode -A
schedule firmware update
dlpar add memory via HMC
shutdown -Fr

Solution – Alternative Approaches

Use these alternatives when the primary fix is blocked by environmental constraints.

redistribute memory across DIMMs
update firmware
contact IBM support

Verification & Acceptance Criteria

Confirm the system meets acceptance criteria after the change.

lparstat -i
lscfg -vp | grep -c DIMM
errpt | head

Rollback Plan

Revert cleanly if regressions appear during validation.

dlpar remove memory
schedule service replacement
lscfg -vp

Prevention & Hardening

Reduce recurrence with monitoring and preventive tuning.

errnotify memory predictive
lsmcode quarterly
capacity planning review

Related Errors & Cross-Refs

Related to CPU deconfiguration, firmware mismatch, and AME tuning loss.

Related tutorial: View the step-by-step tutorial for aix-7.1.

View all aix-7.1 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

IBM AIX 7.2 Hardware events, lsmcode and diag references.