IBM AIX 7.2 – Common Problem 159 – 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

Commands such as df and ls hang for minutes after a NAS controller failover. Operators must reboot LPARs to recover, causing outage.

Environment & Reproduction

Occurs with NFSv3 hard mounts pointing to clustered NAS heads.

mount | grep nfs
oslevel -s
uname -a

Root Cause Analysis

Cause is unresponsive NFS server combined with hard mount semantics, where the client retries indefinitely without timeout.

Quick Triage

Identify hung mounts and PIDs blocked on NFS.

mount | grep nfs

Step-by-Step Diagnosis

Capture deeper evidence to isolate the failure path.

mount | grep nfs
ps -ef | grep -E 'nfs|biod'
nfso -L
rpcinfo -p nasprod
showmount -e nasprod

Solution – Primary Fix

Apply the proven primary fix in a controlled change window.

umount -f /mnt/share
stopsrc -g nfs
startsrc -g nfs
mount -o soft,intr,timeo=20 nasprod:/exp /mnt/share

Solution – Alternative Approaches

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

automount -v
chnfsmnt -f /mnt/share -d nasprod:/exp -t bg,soft

Verification & Acceptance Criteria

Confirm the system meets acceptance criteria after the change.

mount | grep /mnt/share
ls /mnt/share
rpcinfo -t nasprod nfs 3

Rollback Plan

Revert cleanly if regressions appear during validation.

umount /mnt/share
rmnfsmnt -f /mnt/share
mount nasprod:/exp /mnt/share

Prevention & Hardening

Reduce recurrence with monitoring and preventive tuning.

nfso -p -o nfs_v3_iod_readahead=4
chnfs -B
lssrc -g nfs

Related Errors & Cross-Refs

Related to NFSv4 callback failures, idmapd inconsistencies, and DNS PTR mismatches.

Related tutorial: View the step-by-step tutorial for aix-7.2.

View all aix-7.2 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

IBM AIX 7.2 NFS guide, mount and nfso man pages.