🟠 High   ⏱ 5–30 min  Last verified: 19 May 2026
Affected versions: FreeBSD 14

📖 ~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

Mirror remains degraded and redundancy is lost.

Environment & Reproduction

Occurs after hot-swap or metadata mismatch on replacement disk.

gmirror status

Root Cause Analysis

New device not attached correctly or stale GEOM metadata blocks sync.

Quick Triage

Confirm target disk identity and metadata state.

gpart show && geom disk list

Step-by-Step Diagnosis

Inspect gmirror metadata and sync progress counters.

gmirror list
Illustrative mockup for freebsd-14 — gmirror_status
gmirror reports degraded state — Illustrative mockup — Progressive Robot

Solution – Primary Fix

Clear stale metadata and insert new provider into mirror set.

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sudo gmirror insert gm0 /dev/ada1
Illustrative mockup for freebsd-14 — gmirror_rebuild
Rebuilding mirror with replacement disk — Illustrative mockup — Progressive Robot

Solution – Alternative Approaches

Recreate mirror from backup if metadata remains inconsistent.

Verification & Acceptance Criteria

Mirror returns to COMPLETE and sync reaches 100%.

Rollback Plan

Detach faulty replacement disk and keep system in read-mostly mode.

Prevention & Hardening

Standardize disk replacement runbooks and post-repair checks.

Related to GPT mismatch and provider naming changes.

Related tutorial: View the step-by-step tutorial for freebsd-14.

View all freebsd-14 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

FreeBSD GEOM mirror administration references.

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