IBM AIX 7.1 – Common Problem 158 – 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

errpt logs DISK_ERR4 entries against a SAN-attached hdisk, foreshadowing filesystem corruption or VG loss if ignored.

Environment & Reproduction

Occurs on Power LPARs using MPIO with VIOS-presented LUNs.

errpt -a | head -n 200
oslevel -s
uname -a

Root Cause Analysis

Cause is unrecoverable read or path issue on the underlying LUN, often a failing SAN port, cable, or array controller event.

Quick Triage

Correlate errpt entries with MPIO and SAN switch logs.

errpt -a | head -n 200

Step-by-Step Diagnosis

Capture deeper evidence to isolate the failure path.

errpt -a | head -n 200
errpt -j DISK_ERR4 -a | head
lsmpio -ar
lspath -l hdisk5
fcstat fcs0

Solution – Primary Fix

Apply the proven primary fix in a controlled change window.

lsmpio -l hdisk5
chpath -l hdisk5 -p fscsi0 -s disable
chdev -l hdisk5 -a hcheck_interval=60
errclear 0

Solution – Alternative Approaches

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

rmdev -Rdl hdisk5
cfgmgr -l fcs0
importvg -L datavg hdisk5

Verification & Acceptance Criteria

Confirm the system meets acceptance criteria after the change.

lsmpio -ar | grep hdisk5
errpt -j DISK_ERR4 | head
lspath -l hdisk5

Rollback Plan

Revert cleanly if regressions appear during validation.

chpath -l hdisk5 -p fscsi0 -s enable
rmdev -Rl hdisk5
cfgmgr

Prevention & Hardening

Reduce recurrence with monitoring and preventive tuning.

chdev -l hdisk5 -a algorithm=shortest_queue
chdev -l fscsi0 -a fc_err_recov=fast_fail
errnotify

Related Errors & Cross-Refs

Related to PCM driver mismatches, NPIV WWPN changes, and zoning regressions.

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 MPIO documentation, errpt and lsmpio man pages.