On Fri, 2021-11-05 at 10:52 +0100, Martin Steigerwald wrote:
> Hi!
>
> I migrated a Debian Buster to Devuan Chimaera by already install runit-
> init into /target during Debian installation and then switching over
> sources.list to Chimaera.
>
> Debian 11 defaults to usr merge. So the installed system used usr
> merge.
>
> I suppose Devuan is compatible and will remain compatible with that? I
> think it would be necessary as well some users may migrate from
> buster. Or one would have to find a way to undo the merge, but this I
> think is quite error prone.

Devuan defaults to non-merged-/usr as far as I know. You can always
install with merged-/usr on Devuan too using the expert install option.
(Personally I prefer non-merged-/usr remains to be the default.)

> I like to avoid breaking the server VM by undoing usr merge, even tough
> I prefer systems without usr merge. It is easy to do with systems where
> I can use a Devuan ISO for installation, but for this system I had the
> Debian Netinstall ISO and it is what it is.

You can use the dpkg-fsys-usrunmess, with a dpkg release later than or
equal to 1.20.6, see https://wiki.debian.org/Teams/Dpkg/MergedUsr

"For already installed systems (since dpkg 1.20.6) you can also use the
dpkg-fsys-usrunmess program to revert the breakage from these systems
(but beware that it should not be used in systemd's emergency mode)."

(I've used that script on two Debian installations successfully
already.)

Thanks!