Booting a Pi 4 without an external USB drive when it is configured to automount that drive

I have added a line

/dev/sda1 /home/pi/ext ntfs defaults,umask=000,x-systemd.device-timeout=30 0


to /etc/fstab to auto-mount a USB drive that is on /dev/sda1

This works fine.

But if I accidentally forget to plug in the USB drive, booting halts with a message

formatting link

about being in emergency mode

Interestingly, if I then plug the drive in (while the Pi is turned on) and press enter again, it boots normally.

So despite the x-systemd.device-timeout=30 it is stopping dead if the drive is not present.

Originally I had the line

/dev/sda1 /home/pi/ext ntfs defaults 0 0


formatting link
alerted me to the umask parameter to allow access to all files/folders, and the shortened timeout x-systemd.device-timeout=30 instead of 90 seconds.

The only difference from the web page is that I am referring to the drive by /dev/sda1 rather than by its UUID. Is that significant? Is there another parameter that I should be using on the /etc/fstab line?

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Solved it! I should have used the keyword nofail to prevent boot stalling if the drive isn't present:

/dev/sda1 /home/pi/ext ntfs defaults,nofail,umask=000,x-systemd.device-timeout=30 0 0

formatting link
gave me that information.

The consequences of the drive not being present are fairly catastrophic because the Pi is used as a TV recorder which expects to write its recordings to the USB drive, but its better that the Pi at least boots than that it just stops dead in its tracks and throws its toys out of the pram.

The chances of me failing to plug the drive in are fairly remote: it only happened because I moved the Pi from the TV back to my PC to investigate why I'm not getting any sound, either analogue through the 3.5 mm jack or HDMI to the TV, and forgot to bring the external drive with me.

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i had the exact same problem but didn't took the time to investigate. thank you very much for the info, you save me the effort :)

yes, i have somehow the same problem. my chances to forget to plug my usb drive are low, but it happened already!


~{,_,"> indignus LabRat -
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No problem. Glad to be able to help. When I first got a dark grey screen (just discernibly lighter than with the HDMI plug unplugged) I thought the Pi (or more likely the SD card image) was buggered. I'd shut the Pi down cleanly, brought it into the other room, connected it to the PC monitor, plugged in the power supply - what could have gone wrong in those stages? After a couple of times, I brought up a text-boot screen (probably the one that is hidden if you choose Splash Screen in the /boot/config.txt) which reported retries on /dev/sda1. Bugger it! That's the external HDD. Plugging it in allowed the Pi to boot. Phew!

It then took a bit of research to find out what parameters to add to the /etc/fstab entry to make it *always* mount /dev/sda1 if it was present but to skip mounting it without protest if /dev/sda1 was not present.

It was interesting to read the forum where someone had asked the question.

First of all someone says "don't auto-mount, let the user do it". Then someone else says "don't use fstab, use udev rules and usbmount". I could hear Harry Enfield's voice "you don't want to do it like *that*" ;-) Various "solutions" that didn't answer the precise question or requirement and over-complicated things. Eventually someone stepped in and said "just add nofail to the fstab entry" - the voice of sanity: the simplest solution is the best one.

Reducing the timeout was a supplementary, to make sure that the Pi doesn't hang around for so long if the drive isn't present. I could probably reduce it even more.

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