Since the release of Ubuntu 18.04 I’ve been using it a bunch in various VMs. I do love the new minimal install feature. Even though it doesn’t save that much hard disk space it does make things a lot less cluttered, which I absolutely love. Because I work in VMs I’ve been experimenting with migrating OS’s up to 18.04 rather than crushing old VMs, building from scratch, and porting data over. This process has worked almost seamlessly the dozen or so times I’ve done it across many VMs from various different baselines: Mainline 16.04, Mainline 17.10, Ubuntu MATE 16.04. The actual core software itself seems to work perfectly fine out of the box, but as I said it is almost seamless not seamless. There seems to be a bit of a wrinkle with the Ubuntu MATE update with respect to the VirtualBox Guest Additions, specifically with respect to shared folder drives.
I first ran across this in one of my main VMs when I tried the update. Everything went great, I re-applied the guest additions and voilà my shared folder drives mounted and I was in business. The next day when I fired up the VM they were missing. It was a hectic day, so I thought perhaps I had remembered it working so I applied the guest additions again. The drives reappeared. This time I rebooted to confirm it stuck but sadly they did not. I’ve continued to do some experimenting and have come to discover that while they are there the systemd process doesn’t seem to want to start on reboot even though it is set to. So to fix it I just need to do the following command to get them to show up:
sudo systemctl restart vboxadd-service.service
I wasn’t having this problem on Ubuntu 18.04 or Ubuntu MATE 18.04 virgin machines so this was either a problem with the general Ubuntu 16.04 to 18.04 upgrade process or specific to Ubuntu MATE 16.04 to 18.04 upgrade. I therefore went about creating two brand new VMs, one each for mainline Ubuntu 16.04 and one for Ubuntu MATE 16.04 and then went through the upgrade process directly. Those steps are:
- Fresh install OS with 3rd party and upgrades turned on
- Follow https://virtualboxes.org/doc/installing-guest-additions-on-ubuntu/ for installing guest additions
- Shutdown/Power on
- Add user to the vboxsf group (sudo usermod -a -G vboxsf <username>)
- Confirm RW shared folder
- Bring up graphical updater, do any additional updates
- Invoke Upgrade to 18.04 through graphical system:
sudo apt update && sudo apt dist-upgrade
- See if shared folder drive there
- After Update re-apply kernel extensions
- Confirm shared drive
I can repeatably show that mainline Ubuntu 16.04 goes through these updates without this artifact but the MATE version does not. Again, a fresh Ubuntu MATE 18.04 install doesn’t have this behavior at all. I wonder if this write up can shed some light on this problem for the Ubuntu MATE team.