🟠 High   ⏱ 5–30 min  Last verified: 20 May 2026
Affected versions: FreeBSD 12

📖 ~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

Cloned disk boots inconsistently or fails to expose expected partitions, risking downtime and data inaccessibility.

Environment & Reproduction

After cloning to different-sized media, gpart shows warnings and some partitions are unreadable or missing.

Root Cause Analysis

Stale backup GPT headers, geometry mismatch, or interrupted clone process leads to inconsistent partition metadata.

Quick Triage

Run gpart show, gpart recover, and geom disk list to verify header integrity and device size alignment.

Step-by-Step Diagnosis

Compare primary and secondary GPT headers and inspect partition UUID mapping for clone-related conflicts. image_ref=0

Illustrative mockup for freebsd-12 — terminal_or_shell
Inspecting gpart output and disk geometry — Illustrative mockup — Progressive Robot

Solution – Primary Fix

Recover GPT backup header with gpart recover and revalidate partition layout before mounting filesystems. image_ref=1

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Illustrative mockup for freebsd-12 — log_or_config
Reviewing partition table metadata and recovery commands — Illustrative mockup — Progressive Robot

Solution – Alternative Approaches

Recreate GPT table from known manifest and restore data from backups when metadata corruption is severe.

Verification & Acceptance Criteria

All intended partitions are visible and mountable, and boot path operates without partition errors.

Rollback Plan

Switch back to original source disk and postpone clone cutover until partition metadata is corrected.

Prevention & Hardening

Use verified cloning workflows with post-clone GPT checks and documented partition manifests.

Often appears with mountroot prompts, missing labels, and UFS/ZFS import failures after migration.

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

Consult man gpart, FreeBSD disk management guide, and vendor disk migration best practices.

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