📖 ~1 min read
Table of contents
Symptom & Impact
Mirror remains degraded, increasing risk of data loss on next failure.
Environment & Reproduction
Seen after replacement drive metadata mismatch or attach sequence errors.
Root Cause Analysis
New disk is not fully attached or resync process did not complete.
Quick Triage
Verify disk identity, partition table, and current gmirror status.
Step-by-Step Diagnosis
Review gmirror event logs and identify attach/resync blockage.
Solution – Primary Fix
Reattach disk correctly and complete full mirror resynchronization.
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Solution – Alternative Approaches
Migrate to ZFS mirror if lifecycle management requires richer tooling.
Verification & Acceptance Criteria
Mirror reports complete and healthy state with no pending resync.
Rollback Plan
Restore from backup if mirror metadata cannot be repaired safely.
Prevention & Hardening
Standardize replacement runbook and track disk health telemetry.
Related Errors & Cross-Refs
Related to controller remap issues and write-cache consistency faults.
Related tutorial: View the step-by-step tutorial for FreeBSD 12.
View all FreeBSD 12 tutorials on the Tutorials Hub →
Browse all common problems & solutions on the Tutorials Hub.
References & Further Reading
gmirror(8), geom(4), and FreeBSD storage resilience documentation.
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