IBM AIX 7.3 – Common Problem 018 – 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

mksysb backup to /dev/rmt0 fails with I/O error mid-stream.

Environment & Reproduction

IBM AIX 7.3 LPAR exhibiting Backup / mksysb tape issues under standard PowerVM workloads.

lsdev -Cc tape
errpt | grep mt

Root Cause Analysis

Tape drive media error or SCSI bus reset interrupts the mksysb stream.

Quick Triage

Confirm scope with errpt, recent changes, and subsystem state via lssrc.

tctl -f /dev/rmt0 status
errpt | grep TAPE

Step-by-Step Diagnosis

Verify tape drive status with tctl and check errpt for media events.

errpt -a | grep -A5 TAPE
tctl -f /dev/rmt0 rewind

Solution – Primary Fix

Replace media and rerun mksysb after cleaning the drive.

mksysb -i /dev/rmt0

Solution – Alternative Approaches

Target a NIM master with mksysb to disk image instead of tape.

Verification & Acceptance Criteria

Confirm subsystem returns to RUNNING state and errpt shows no new entries.

lsmksysb -l -f /dev/rmt0

Rollback Plan

Restore prior configuration from mksysb or alt_disk_install clone if the fix regresses.

tctl -f /dev/rmt0 rewoffl

Prevention & Hardening

Encode the fix in NIM customisation scripts and monitor via topas/nmon.

smit mksysb  # weekly NIM-based mksysb

Related Errors & Cross-Refs

errpt LABEL=TAPE_ERR1; media errors

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

AIX backup strategies with mksysb and NIM