[arch-general] pacman new generation

[C Anthony Risinger]

On Nov 22, 2011 1:30 PM, "Bernardo Barros" <bernardobarros2 at gmail.com>
wrote:
>
> If I still may:
>
> roll-back and reproducible configuration was already proposed in the past?
>
> The idea raised by Nix devs was the a purely functional approach was a
> way to implement it. Of course people can have similar ideas with
> other techniques.
>
> If it a very practical question because I'm sure all Arch users in
> some point or another had to do a roll-back after a complex system
> update, and then they find themselves in a difficult situation to
> figure out how to revert all those changes.
>
> Pro Audio users, for instance, might want to have their system
> configuration in a state just before the change that broke lv2 support
> on Ardour.
>
> Nix approach may be not the only one, but their ideas let people see
> the difference between same packages build with different libs, or
> know to set a exact system configuration more easily.

The only clear way to achieve clean rollbacks is to snapshot at the FS
level ... otherwise things get real complicated, real fast.

Some packages are one-way only, eg. Pacman 3.5 upgrade to DB, and
"rollback" means saving the original, etc ...

As already touched in the thread, btrfs makes this trivial.
`mkinitcpio-btrfs` will provide 95% of what's needed already.  The hook
could definitely use some love but it fulfills the suggested use case
nicely, and also allows for comparison between snapshots.

C Anthony