CompTIA Linux+ (XK0-006)TroubleshootingHard
A server fails to boot normally and drops into a systemd emergency shell. The journal shows: "[TIME] Timed out waiting for device /dev/sdb1." Investigation reveals /dev/sdb1 is an external USB drive that is not always connected, but it has a standard entry in /etc/fstab. Which fstab mount option should be added to that entry to prevent this boot failure when the device is absent?
- Adefaults
- Bnofail
- Cro
- Dnoauto
Show answer & explanationAnswer & explanation
Correct answer: B. nofail
The nofail option tells systemd to continue booting even if the device fails to mount, rather than treating it as critical and blocking the boot process. noauto would prevent automatic mounting entirely (even when the device is present), which changes intended behavior rather than fixing the boot-blocking issue.
Why the other options are wrong
- A. defaults is the standard option set already likely in use and does not solve the timeout problem.
- C. ro only mounts the device read-only; it doesn't address the boot-blocking timeout.
- D. noauto prevents the drive from auto-mounting even when it IS connected, which isn't the desired behavior.
fstab nofail Option
The nofail mount option in /etc/fstab tells systemd not to block booting if that particular filesystem entry fails to mount, useful for optional or removable devices.
- Prevents emergency mode when a device is legitimately absent
- Often paired with 'noauto' for devices mounted manually or on demand
- Contrast: default fstab behavior treats a failed mount as critical, halting boot
Memory trick: 'nofail' says: don't fail the whole boot just because one drive didn't show up.