fstab — /etc/fstab and mounts

A bad /etc/fstab entry can drop the next boot into emergency mode — and the upgrade's reboot is often the first boot in a long time.

At a glance

ID	fstab
Category	Storage
Needs root	no
Needs programs	findmnt
Compares with a snapshot	yes
Options	0

What it checks

• findmnt --verify: errors and warnings in /etc/fstab (unknown devices, missing mount points, unsupported filesystem types, bad options).
• With a snapshot: filesystems that were mounted before and aren't now.

Findings

Severity	Finding	What to do
critical	/etc/fstab has N errors	Fix the entries named in the evidence before rebooting.
critical	findmnt --verify failed	Run findmnt --verify yourself to see why.
warning	/etc/fstab has N warnings	Review the entries named in the evidence.
warning	mount was mounted before the upgrade but is not now	findmnt --fstab MOUNT; sudo mount MOUNT.
info	Some fstab entries could not be fully verified without root	Run as root.

Compared with a snapshot

The snapshot records the mounted filesystems (virtual ones are left out).

Commands it runs

findmnt --verify
findmnt -rn -o TARGET,SOURCE,FSTYPE

Limitations

• findmnt --verify checks what it can see: a device that's just not plugged in (an external disk) looks the same as one that's gone.
• Mounts managed outside fstab (systemd mount units, autofs) are only covered by the snapshot comparison.

Options

This check has no options. Turn it off with enabled: false under checks: fstab: in the configuration file, or for one run with --skip fstab.