Snapshotting for rollback after updates was[ Re: Drawing lessons from fatal SELinux bug #1054350]

[Simo Sorce]

On Sun, 2014-01-26 at 13:13 -0700, Chris Murphy wrote:
> On Jan 26, 2014, at 11:41 AM, Simo Sorce <simo at 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?

It is not.

> > 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.

Users should not expect miracles either.

Simo.

-- 
Simo Sorce * Red Hat, Inc * New York