Upgrade guidance

[Ben Scott]

On Mon, Oct 20, 2008 at 9:03 AM, Jefferson Kirkland
<numberwhun at gmail.com> wrote:
> I have a few machines here at work (development, testing and Production
> machines) that need to be upgraded to the latest version of Fedora (FC9).
> The machines are all presently running FC6.

#ifdef MAKE_THINGS_EVEN_MORE_COMPLICATED

  What's driving the upgrade request?  Just the desire to remain
current with updates, or something else?

  FC6 was released Oct 2006 and has been unmaintained for roughly a
year already.  If you're upgrading just to get back on a maintained
release and would rather you didn't have to, CentOS/RHEL is prolly
more appropriate for your needs.    If so, you may want to consider a
"lateral migration" to CentOS/RHEL.  The much longer release cycle
means you need to do base system upgrades much less often.  You'll be
going through some upheaval anyway, so this would be the time to do
it.

  It may even be possible for CentOS to run an automated upgrade from
Fedora.  Fedora is basically the old Red Hat Linux product, and I know
CentOS at least used to be able to upgrade a system from RHL.  This is
just speculation on my part, though.

  If you want to go to FC9 because you need some new features in that
release, then CentOS/RHEL is probably *not* you.  To get that long
release cycle and stable software configuration, CentOS/RHEL sacrifice
staying current with the latest and greatest upstream features.  For
the most part, you get security and bugfixes only.  Sometimes features
are backported, but that's the exception, not the rule.

#endif

> I don't want to assume that going directly from FC6 to FC9 is the best course when I
> don't know for sure.  Any guidance you can provide is greatly appreciated.

  As mentioned above, FC6 is unmaintained for about a year now.  I
would speculate that the FC6 -> FC9 scenario hasn't been well tested
by the Fedora people (if at all).  (Maybe someone here knows better
and can speak more definitively.)  So you may run into "unexpected"
problems.

  And even if the distribution does its job perfectly, FC6 to FC9 is a
significant change anyway, so you're likely going to see breakage just
from things like major changes in upstream packages.

  Do you have any third-party (i.e., not Fedora) packages installed?
If so, you'll want to test those with an FC9 system before deployment.
 You'll likely need to rebuild from source, and/or obtain updated
builds from a packager.  There may also be dependency issues (if
third-party packagers depend on things not in FC9).

> Also, at present, none of the machines have a monitor hooked up as they are
> in a rack in a server room.  All work is done remotely on these machines,
> but I do have physical access to them if need be.

  Depending on how many installations you have and how strict a
configuration management policy you follow, you may want to just plan
on being "hands-on".  If there are 10s or more of the same config,
automation is worth it, but if this is just a bunch of one-off's, not
so much.  Unless you have sophisticated remote management tools
(remove console and CD).

  One approach to consider would be pre-configuring tarchives or disk
images of an upgraded system, and then just blow away the software
directories/partitions for deployment.  Again, it depends on specifics
of the environment.

On Mon, Oct 20, 2008 at 9:15 AM, Jefferson Kirkland
<numberwhun at gmail.com> wrote:
> I have done some research already and see that htere is a yumupgrade
> option.

  In theory doing a "live upgrade" (yum to upgrade the running system)
is "not official supported".  The bootable installer (CD, DVD, net
boot, etc.) is the only "official" way to do things.

  However, I've been told the live upgrade does work very well in most
cases, and basically just does the same thing the bootable installer
does.  From what I've seen, that is indeed the case: The bootable
installer mainly relies on the scripts in the packages to handle
migration of stuff.

  However again, I'm not sure "most cases" includes jumping several
releases.  Fedora people tend to like to keep up-to-date with the
latest and greatest packages, and so the "delta" for a yum upgrade on
a live system would be smaller.  They might not have your scenario in
mind.

  However again again, as stated above, I'm not sure FC6 -> FC9 is
well tested anyway, so you may be in that boat either way.

  The best thing to do is probably to reproduce your existing FC6
systems in a test/simulation environment, and see how it goes.

> I am a little weary about it due to the large difference in
> versions and also that its kind of like doing a bios upgrade in that you DO
> NOT power off or stop the upgrade in any way.

  If you're upgrading the base system, that will be the case
regardless of how you do it.  You're talking about ripping and
replacing major components (kernel, system/C library, etc.).  If that
gets interrupted, you're hosed.  I've seen it happen, and it ain't
pretty.  So make backups.  Test them, too, so you're prepared to
restore them if needed.

  "Always mount a scratch monkey."

-- Ben