non-destructive ports/packages update

[Chris Rees]

On 21 Apr 2013 02:13, "Perry Hutchison" <perryh at pluto.rain.com> wrote:
>
> Xin Li <delphij at delphij.net> wrote:
>
> > On 4/19/13 11:34 PM, Perry Hutchison wrote:
> > > I'm looking for a way to move everything connected with ports and
> > > packages aside, so that I can start fresh but with the ability to
> > > easily roll it back when things go badly (as they surely will).
> > >
> > > I have in mind to something like this:
> > >
> > > # cd /usr
> > > # mkdir old
> > > # mv ports local old
> > > # mkdir ports local
> > > # cd /var/db
> > > # mkdir old
> > > # mv ports pkg old
> > > # mkdir ports pkg
> > >
> > > Is there anything else that needs to be saved before fetching a
> > > new ports tree and starting to build things (or install prebuilt
> > > packages)?
> >
> > If you use ZFS, it's possible to take snapshot, then install new
> > ports, then if something blows up, you can rollback.
> >
> > With UFS, it's still possible to take snapshot but rollback is not
> > atomic.
>
> I'm aware of filesystem snapshots, but I only want to checkpoint the
> ports and packages, not the whole filesystem -- a rollback needs to
> be fast, easy, and obviously correct; preserve the failure logs; and
> not undo changes that may have been made elsewhere in the meantime.
> (BTW I don't use ZFS:  the machine doesn't have enough memory, and to
> me ZFS -- especially on 8.x -- doesn't yet seem sufficiently proven.)
>
> > If you use portmaster, it can save packages (I think portupgrade
> > can do it too).  But this approach depends on the fact that the
> > port is well written, and is not atomic in terms of package set.
>
> And then a rollback requires re-installing the saved packages, which
> is surely slower than moving a few directories and/or files around.
>
> The question is, what (if anything) else -- besides /usr/ports,
> /usr/local, /var/db/ports, and /var/db/pkg -- needs to be checkpointed?

Are you installing any drivers?  You may need to back up /boot too.

Chris