🔴 Critical   ⏱ 5–30 min  Last verified: 20 May 2026
Affected versions: FreeBSD 13

📖 ~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

ZFS cleanup automation on FreeBSD 13 can cause data loss when dataset selection logic is unsafe.

Environment & Reproduction

Unexpected snapshots or child datasets disappear after scheduled prune jobs run.

Root Cause Analysis

Broad glob patterns, missing dataset allowlists, and untested destructive commands in scripts.

Quick Triage

Review cron logs, script arguments, and zfs history to identify exact deletion commands executed.

Step-by-Step Diagnosis

Stop scheduled pruning and snapshot current state immediately. image_ref=0

Illustrative mockup for freebsd-13 — terminal_or_shell
Listing snapshots and datasets before pruning — Illustrative mockup — Progressive Robot

Solution – Primary Fix

Rewrite script with explicit dataset list, dry-run mode, and conservative retention logic before re-enabling. image_ref=1

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Illustrative mockup for freebsd-13 — log_or_config
Reviewing pruning script and retention configuration — Illustrative mockup — Progressive Robot

Solution – Alternative Approaches

Disable offending cron entry until validation completes and keep manual approval for destructive runs.

Verification & Acceptance Criteria

Store retention policy in a strict config file and validate dataset names against an allowlist.

Rollback Plan

Networking is secondary, but ensure backups replicate over permitted channels before deletion workflows.

Prevention & Hardening

Run dry-run output checks and compare intended deletion list against expected retention policy.

Add immutable backups, alert on destroy operations, and require two-person review for script changes.

Related tutorial: View the step-by-step tutorial for freebsd-13.

View all freebsd-13 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Consult man zfs, man cron, and operational best practices for snapshot lifecycle management.

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