🟡 Medium   ⏱ 5–30 min  Last verified: 19 May 2026
Affected versions: FreeBSD 15

📖 ~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

Expected dataset path is empty after reboot, causing service startup failures and missing data views.

Environment & Reproduction

Occurs when legacy fstab entries or pre-created directories interfere with ZFS mount semantics.

zfs list -o name,mountpoint,canmount,mounted
cat /etc/fstab
mount | grep zfs

Root Cause Analysis

Mountpoint collision between ZFS property and traditional mounts prevents automatic attach at boot.

Quick Triage

Check canmount and mountpoint inheritance values.

zfs get -r mountpoint,canmount 
service zfs status

Step-by-Step Diagnosis

Trace boot mount ordering and identify conflicting path owner.

zpool history | tail -n 40
dmesg -a | grep -i zfs | tail -n 50
ls -ld
Illustrative mockup for freebsd-15 — terminal_or_console
Diagnosis commands for post 157 — Illustrative mockup — Progressive Robot

Solution – Primary Fix

Remove conflicting fstab line and set canonical ZFS mount properties.

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cp /etc/fstab /etc/fstab.bak
vi /etc/fstab
zfs set canmount=on 
zfs set mountpoint= 
zfs mount -a
Illustrative mockup for freebsd-15 — log_or_dashboard
Fix validation evidence for post 157 — Illustrative mockup — Progressive Robot

Solution – Alternative Approaches

Use canmount=noauto for staged datasets and mount from service hook.

zfs set canmount=noauto 
zfs mount

Verification & Acceptance Criteria

Dataset mounts correctly after reboot and dependent services start cleanly.

mount | grep 
service -e | grep 
shutdown -r now

Rollback Plan

Restore saved fstab and previous dataset properties if unexpected mount behavior appears.

cp /etc/fstab.bak /etc/fstab
zfs inherit mountpoint

Prevention & Hardening

Keep all ZFS-backed paths out of fstab and codify mountpoint conventions.

zfs get -r mountpoint,canmount 
grep -v '^#' /etc/fstab

Related to jailed datasets and delegated mount rights.

Related tutorial: View the step-by-step tutorial for freebsd-15.

View all freebsd-15 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

zfsprops manual and FreeBSD boot sequence documentation for ZFS mounts.

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