[TAG] Upgrading from RHEL v3 to v5

[Thomas Adam]

On Mon, 26 Mar 2007 06:41:07 -0500
Jesse Fitzgerald <jesse at nursingnet.com> wrote:

> I want to upgrade to version 5.0. I?m a bit anxious though. I only
> have a few users, but have spent a lot of time getting everything
> running well on my box. My question: If I install Red Hat Enterprise
> V5 using the upgrade option via the anaconda installer, will I loose
> any of my data or applications? I know that doing a clean wipe and
> reinstall is the BEST solution, but if possible I would like to
> upgrade.

Actually, it's not the best solution at all.  In doing that you will
invariably wipe out all manner of settings -- some of which you might
not have realised to backup at all (hint:  some application use /var as
a dumping ground which tends to trick a number of people when they
backup their configurations in an attempt to do a window-esque style of
""upgrading""; wholly wrong, IMO).

Upgrading will replace binaries in /usr, yes.  That's a premise you
except when you upgrade, of course.  If you have custom binaries you
yourself have compiled from source which install to /usr then you might
be able to tell your package manager (rpm in this case) not to touch
certain files -- you certainly can with apt under Debian for instance,
but it's been some time since I last an RPM system with any great
vigour.

> Here is what I?m specifically concerned about loosing:
> Apache, MySql, PHP, Qmail, Vpopmail, and various other small
> applications (Webalizer, etc?). All of the above have been compiled
> from source. I?m also concerned about stuff in /usr /usr/home /etc
> and /var being overwritten.

Well, as I mentioned above, stuff in /usr and /var will get overwritten.
Full-stop.  This is why you upgrade, after all.  The best solution I can
offer you is to backup the configuration files for all of the programs
you've listed above, reinstall the compiled applications from source,
and just have done with it.

This ought not to be much of an option though, assuming the compiled
applications you yourself have installed haven't overwritten files which
you might have previously installed via rpm.  I.e., if you have apache
installed then it will overwrite your custom package, and likewise, if
any of the dependencies in the upgrade cause apache to be installed
that too will overwrite your files.

This is where the advantage of installing to /usr/local (typically the
default with PREFIX= or --prefix= depending on whether you use make
or./configure respectively) comes in handy.  It's policy for packages
not to install files there.  You may of course already meant /usr/local
for your compiled applications; it's non-obvious from your
descriptions, so I am taking you verbatim.

Oh, and as a parting comment, one of the reasons why people split /usr
and /home onto separate partitions is also to make things like
upgrading work easier -- i.e., not mounting /home is often beneficial
so that nothing really can be deleted or overwritten, etc.  (A poor
example in this case, but the essence of it applies.)

-- Thomas Adam