Basic question about reverting

I would like to backup my TemplateVM in between each installation of software. Would this procedure work? Reverting as described in the documentation seems harder to me.

  • Clone Debian-10 to Debian-10a.
  • Install software.
  • Clone Debian-10a to Debian-10b.
  • Install other software.
  • Clone Debian-10b to Debian-10c.
  • Install other software.
  • Delete Debian-10a.
  • Clone Debian-10c to Debian-10d.
  • Install other software.
  • Realize that there is a problem and I want to undo more than one step. So I delete 10c and 10d and clone another 10c from 10b?

One reason I was worried is that the clones show 0 disk space usage.

This scheme looks fine to me.
Alternatively, reverting should also be possible, but you would first need to configure enough automatic snapshots, and reboot your VM every time to force the creation of the backup.

0 disk usage typically shows for newly created AppVMs, because they have nothing in their /home directory. Are you sure these are TemplateVMs?

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Thanks! Yes they are. But now I realize it only shows 0MB at first. It’s a normal size once I start it or make changes.

Related to that, say I made a AppVM based on Debian-10a. Then in the future, I’ve installed 10 applications and I’m on Debian-10k. I can just change the AppVM to be based on Debian-10k and I would be able to choose any of the 10 applications to run in it? (Also by then I want to delete Debian-10a because I don’t have more use for it.)

Yes, it should work. Some people even change Fedora-33 to Fedora-34 and Debian-10 to Debian-11 (not sure whether it can have any bad consequences. Backups should always help).

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