📖 ~1 min read
Table of contents
Symptom & Impact
Applications fail writes as ext4 remounts read-only to protect integrity during storage fault conditions.
Environment & Reproduction
Seen on aging disks, unstable virtual storage, or abrupt host resets with pending journal metadata.
Root Cause Analysis
Kernel detects repeated block I/O errors and forces safe remount to prevent further corruption.
Quick Triage
Stabilize workload, gather dmesg evidence, and assess whether immediate failover is required.
Step-by-Step Diagnosis
Correlate kernel I/O errors with smartctl metrics and filesystem check requirements.
Solution – Primary Fix
Schedule maintenance, run fsck offline, replace failing storage if needed, and restore write mount mode.
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Solution – Alternative Approaches
Fail over to replica, restore from backup, or migrate data to healthy block devices.
Verification & Acceptance Criteria
Filesystem remains read-write under stress test and no new I/O faults appear in logs.
Rollback Plan
Return services to standby host if repaired disk shows recurring media or controller errors.
Prevention & Hardening
Monitor SMART health and enforce replacement thresholds before predictive failure becomes outage.
Related Errors & Cross-Refs
Cross-reference mdraid degradation and inode corruption with companion Ubuntu storage tutorial.
Related tutorial: View the step-by-step tutorial for Ubuntu 18.04 LTS.
View all Ubuntu 18.04 LTS tutorials on the Tutorials Hub →
Browse all common problems & solutions on the Tutorials Hub.
References & Further Reading
Use ext4 admin docs, smartmontools guidance, and Ubuntu filesystem recovery documentation.
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