Re: [gentoo-user] Heads Up - switching to profile 17.1 is not as easy as it sounds

[Rich Freeman]

On Tue, Jun 11, 2019 at 7:21 AM Davyd McColl <davydm@×××××.com> wrote:
>
> On Tue, 11 Jun 2019 at 12:34, Helmut Jarausch <jarausch@××××××.be> wrote:
>>
>> I had some trouble switching to the new profile 17.1.
>> Following the advice in the news item didn't suffice.
>>
>
> first off, `emerge -v1 /lib /lib32` didn't work out because I had an old library in there I
> had to remove with `emerge --depclean` first. I also have an old install of sickbeard, which
> I had to remove from world for the same reason: `emerge -v1 /lib /lib32` would just complain
> about not being able to find an installable source (my words -- can't remember the original
> terms), but it didn't really look like an error -- all green text.

I've updated two hosts.  One went very smoothly, but it is a fairly
dedicated host.  One had a few issues, and it has a LOT of history.

I found that anything 32-bit tended to cause more trouble, and I had a
few orphans as well.  It wasn't a huge deal.

I think a big part of that is that before I did ANYTHING I took a lot
of steps to clean up.  I ran depclean and revdep-rebuild as a start.
I reviewed all the migration tool output and anything that looked
non-essential was depcleaned.  When I did the 32-bit rebuild anything
that was giving me trouble was traced back to whatever pulled it in
and depcleaned (I forget if I did that up-front or if I just deleted
the offending library and depcleaned the rev dep later - obviously
don't do that for anything you care about).

On a more dedicated host/container/etc I suspect you won't have many
issues, because you're not going to have a huge pile of legacy stuff
lying around with complicated dependency relationships.

Some of my rebuild and depclean issues were resolved with --backtrack
and --with-bdeps=y.

In general a good principle is that anytime you want to change
profiles take some time to do some housekeeping.  The less junk you
have on your system, the less there is that can go wrong.

On my one host I also took the opportunity to decide whether I REALLY
needed wine.  That is a TON of 32-bit stuff you otherwise probably
don't need.  After removing it you need to clean out package.use
because we don't have soft USE dependencies yet.

And of course before I did anything I took a zfs snapshot of my root
filesystem which only contains the OS for the most part.  So, if I ran
into serious issues a rollback would probably have been a one-liner
(I'm guessing that I'd do that from a rescue disk just to keep daemons
with stuff in /var from going nuts).

Overall it went better than I was anticipating actually.  We haven't
had a migration like this one in a while, but I do think that the
risk-level of this one was a bit undersold.  Restructuring all your
libraries is obviously a risky task and while you shouldn't be
alarmist it is something that has a lot of potential to go wrong.  To
be fair, the news item does say that you should do a backup.

-- 
Rich