IBM AIX 7.3 – Common Problem 62 – 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

VIO Server reports queue_depth full and client LPAR sees slow I/O on vSCSI hdisk.

Environment & Reproduction

Mapped backing devices exceed vhost queue depth on VIOS 7.3.

Root Cause Analysis

queue_depth on vtscsi target lower than aggregate client demand.

Quick Triage

Run lsmap -all on VIOS and iostat -D on client for service times.

Step-by-Step Diagnosis

Use viostat and chdev -l hdiskN -a queue_depth=32 on VIOS.

Solution – Primary Fix

Increase queue_depth on backing hdisk and reboot client to pick up.

Solution – Alternative Approaches

Migrate workload to NPIV vfchost path with dedicated zoning.

Verification & Acceptance Criteria

iostat avgsv on client drops below baseline and no FC queue errors.

Rollback Plan

Revert queue_depth with chdev -l hdiskN -a queue_depth= -P.

Prevention & Hardening

Size queue_depth using DS8K/SAN vendor guidance and monitor.

Related Errors & Cross-Refs

FCP_ARRAY_ERR, slow vSCSI service times.

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

PowerVM VIOS performance and tuning guide.