π ~1 min read
Table of contents
Symptom & Impact
RAID redundancy is lost and risk of data loss increases until rebuild completes.
Environment & Reproduction
Happens when one member is marked faulty after abrupt reboot or I/O timeout.
Root Cause Analysis
Array metadata mismatch or transient disk errors prevent clean member activation.
Quick Triage
Check /proc/mdstat and smart data before forcing any array operation.
Step-by-Step Diagnosis
Inspect mdadm details, identify failed member, and confirm disk health signals.
Solution – Primary Fix
Re-add healthy member, monitor rebuild progress, and validate filesystem integrity.
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Solution – Alternative Approaches
Restore from backup if multiple members are unstable or data inconsistencies appear.
Verification & Acceptance Criteria
Array reports clean state and no pending resync errors remain.
Rollback Plan
Stop rebuild and revert to backup restore workflow if additional faults appear.
Prevention & Hardening
Enable SMART alerts, periodic scrubs, and tested UPS shutdown handling.
Related Errors & Cross-Refs
Related alerts include md mismatch count growth and repeated ATA resets.
Related tutorial: View the step-by-step tutorial for Ubuntu 14.04 LTS.
View all Ubuntu 14.04 LTS tutorials on the Tutorials Hub β
Browse all common problems & solutions on the Tutorials Hub.
References & Further Reading
See mdadm administration, SMART, and Linux RAID recovery resources.
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