Am 26.01.2014 21:13, schrieb Chris Murphy:
On Jan 26, 2014, at 11:41 AM, Simo Sorce <simo(a)redhat.com>
wrote:
> I never said it won't work in absolute, it probably will work ok in many
> cases, just to cause incredible issues in others.
>
> It is a fine tool in the hands of an expert that knows how to check
> whether reverting to a snapshot is safe.
Why is the snapshot case any different from a user who reverts doing a clean install or
yum downgrade?
because the snapshot restores *a whole filesystem* and not only the affected application?
* restore a snapshot of /usr and you have fun with /var/lib/rpm
* restore a snapshot of /var/lib/ without /usr and you have fun with the rpmdb and others
* restore a snapshot of /usr without /etc and you *may have* random fun
and there are *hundrets* of such combinations where the last thing you
really would want is restore a snapshot because you have no plan about
the real-world impact in doing so
> It is not going to be a good solution for non-expert users
though
> *unless* you provide system APIs that *all* applications use to signal
> when they are doing irreversible changes so that the user can be warned
> about potential data loss right when he asks the system to revert a
> snapshot.
Developers should not be sneak attacking non-expert users with file format changes that
aren't well
announced in advance of consequences they probably won't be able to read their data
if they downgrade
the application
the perfect world won't happen, sad but true