Installation of Ubuntu in VM fails: "Unable to finalize remainig file systems, loop devices,ignoring."

Apps and Virtualization
1

Hi - I am Marc and quite new to TrueNAS.

I have installed TrueNAS Core (TrueNAS-13.0-U6.2). Bare metal on a Fujitsu Esprimo D956, 16 GB RAM. 1 x 120GB SSD, 2 x 1TB HHD.

Now I would like to install Linux in a virtual machine so that I can install Docker.
To do this, I created a virtual machine on the SSD. The virtual machine is running.

So, I’m trying to install Ubuntu (ubuntu-24.04-live-server-amd64.iso) in the virtual machine. And I can’t do that. I’ve already looked for a solution here in the forum and also tried Google. Without success.

I started the installation on the virtual machine via VNC (more precisely: I use UltraVNC Viewer under Windows).

As far as I can sys, the system will be installed, thats are last lines from the protocoll:

Installation complete!
(…)

updating initramfs configuration
configuring target system bootloader
installing grub to target devices
copying metadata from /cdrom
final system configuration
calculating extra packages to install
configuring cloud-init
downloading and installing security updates
curtin command in-target
restoring apt configuration
curtin command in-target
subiquity/Late/run:

After reboot

[FAILED] Failed unmounting cdrom.mount - /cdrom.
Please remove the installation medium, then press ENTER:

After pressing Enter

[FAILED] Falled unmounting cdrom.mount - /cdrom.
Please remove the installation medium, then press ENTER:

[1542.527872] (sd-umoun (20074]: Failed to unmount /run/shutdown/mounts/18feacc1168b6957: Device or resource busy
[1542.531102] shutdown [1]: Could not detach loopback /dev/loop3: Device or resource busy
[1542.531193] shutdown [1]: Could not detach loopback /dev/loop2: Device or resource busy

[1542.531265] shutdown [1]: Could not detach loopback /dev/loop1: Device or resource busy [1542.536620] shutdown [1]: Unable to finalize remaining file systems, loop devices, ignoring.

And then
A selection menu now appears: “Try or Install Ubuntu Server”, “Boot from next volume”, “UEFI Firmware Settings”.

I selected “Try or Install Ubuntu Server”, … .

The screen will then appear where you can select the language and the installation will begin again.

I would be happy if someone could point me in the direction of where the problem is. If you need further information, I will of course provide it.

Thanks so far. Now I’m looking forward to your answers.

Marc

Note: This text was automatically translated from German.

2

The VM is just booting from the CD-ROM/iso after the install appears complete as it failed to unmount the iso. After install appears complete and you hit ENTER you can probably get away with powering off the VM and then delete the CD-ROM device. Hopefully, it will boot into your new Ubuntu install.

But you may have post-install problems as reported on the old forum. e.g: Can not move mouse in Ubuntu VM; keyboard works | TrueNAS Community

Does it have to be Ubuntu? Installing Alpine Linux in a VM is much lighter - no systemd/snap bloat - and one of the few Linux distros that has an active serial console. Alpine Linux works fine as a docker host. You will still have to use network shares to share data between Linux VM and TrueNAS host.