IBM AIX 7.1 – Common Problem 091 – 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

Database performance drops; iostat shows high aio queue depth.

Environment & Reproduction

Triggered when aio_maxservers is too low for the workload.

Root Cause Analysis

AIO kernel servers cannot drain submitted I/Os fast enough.

Quick Triage

Run iostat -A and pstat -a | grep aio to see server counts.

Step-by-Step Diagnosis

Check ioo -L | grep aio_ for current min/max server tunings.

Solution – Primary Fix

Raise limits with ioo -p -o aio_maxservers=200 -o aio_maxreqs=8192.

Solution – Alternative Approaches

Alternative: enable Fast Path AIO with ioo -o posix_aio_fastpath=1.

Verification & Acceptance Criteria

Verify with iostat -A that AIO wait drops and queue clears.

Rollback Plan

Roll back via ioo -d aio_maxservers if Oracle/DB2 misbehaves.

Prevention & Hardening

Match aio_maxservers to vendor sizing (Oracle, DB2, Informix).

Related Errors & Cross-Refs

Related: 0517-072 AIO errors and LIB_AIO entries in errpt.

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 Docs: Asynchronous I/O tuning on AIX.