Category Archives: Linux

Fixing Ubuntu VFS: Can’t find ext4 filesystem error on reboot

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TL;DR: When you mount drives in your /etc/fstab, don’t use the drive designations (/dev/sda, /dev/sdb, etc.) because they can change upon reboot. You should label the drives instead and use those labels in /etc/fstab.

List your drives:

fdisk --list | more

Give each drive you need to mount a label using tune2fs. For example:

tune2fs -L EXAMPLE_LABEL /dev/sdb

Change /etc/fstab to use the labels. From:

/dev/sdb  /my_disk ext4 defaults 0 0

To:

LABEL=EXAMPLE_LABEL /my_disk ext4 defaults 0 0

Reboot.

OK, now to the blah, blah, blah part:

Today I learned that the drives can get detected in a different order on each reboot, so the designations (/dev/sdb, /dev/sdc, etc.) could change. I’m not sure how I’ve worked with Linux all these years and not clued into that, but here we are.

I have a desktop system running Pop!_OS 20.10, which is based on Ubuntu 20.10. My system has three internal drives and one external USB. Along with root (/), one internal drive is mounted as /data, and the other as /reference. Yes, they are both one big partition each.

A few weeks ago when I updated the system from 20.04 to 20.10 and rebooted, I was hosed. The system said it couldn’t find the ext4 file system. After a lot of googling, casting about, and fixing things that were a problem without being the problem, I noticed that the mounts for the internal drives were all screwed up. My /data drive was there, but it contained the contents of /reference. The /reference drive was gone. Fortunately I still had my root drive.

Looking at /etc/fstab and comparing it to the output from fdisk –list, it was all screwed up. Somehow the mount points were pointing to the wrong devices. I fixed them, rebooted, and I was on my way. Turns out I didn’t really fix it, I just got lucky on that reboot.

Today I had several workspaces going and performance started to get weird. I figured I’d just stop where I was and reboot.

…and got the same issue again. Couldn’t find the ext4 file system. The contents of /etc/fstab looked wrong compared to fdisk –list again. I wondered why fstab kept getting reverted or something, I fixed it, rebooted, and… got the error again!

Looking at the fdisk –list output again, I noticed that the disks has moved around. What was /dev/sdc on last boot was now /dev/sdd. The prior /dev/sdb was now /dev/sdc. That’s when I learned that this was apparently a thing, and I should be using the disk UUID or a label in /etc/fstab.

I figured labeling would be easier. I looked at the output from fdisk –list again and figured out which device was the data drive and which was reference. I then labeled them:

tune2fs -L DATA_DISK /dev/sdd
tune2fs -L REF_DISK /dev/sdc

I then changed /etc/fstab to use the labels:

LABEL=DATA_DISK /reference ext4 defaults 0 0
LABEL=REF_DISK /reference ext4 defaults 0 0

Rebooted, and I’m back!

Removing Objects in a Photo with Gimp

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This ended up being a couple of extra steps beyond just Googling, so I wanted to put it out there for the next person.

I found these instructions on using the Gimp plugin Synthesizer to remove objects to be pretty useful, though it looks like some of the menu options have moved around in Gimp 2.8.

Getting the Synthesizer plugin installed correctly on Ubuntu took a couple of tries. Here are great instructions for adding a PPA to your config so you can just use a couple of apt-get commands to install Gimp and many useful plugins, including Synthesizer. It came down to this:

sudo add-apt-repository ppa:otto-kesselgulasch/gimp
sudo apt-get update
sudo apt-get install gimp
sudo apt-get install gimp-plugin-registry

Good luck!