[CentOS] upgrading from CentOS 7 to 8

Tue Oct 1 18:32:15 UTC 2019
Elliot <elliot.li.tech at gmail.com>

On 10/1/19 10:57 AM, MAILIST wrote:
>> Your answer has nothing to do with the original question which is related
>> to upgrade method and not condition for reinstalling without loosing
>> data.
> After 40 years of upgrading many different operating systems,
> Windows (from 3.1 to 10), CentOS 6 to 8, Ubuntu, Fedora, Red Hat,
> AT&T Unix, VAX VMS; I have never observed an upgrade from one major
> version to the next to work.  The last one I tried using their "upgrade
> process" was Ubuntu 18 to 19.  Didn't work.

Not trying to undermine what you said. I totally believe that different
situations deserve different solutions.

In my career, I've managed many Debian, Ubuntu, Fedora, and CentOS
systems, and I found that in-situ upgrading of Debian, Ubuntu, and
Fedora are usually easy and convenient. If you are using 3rd party
repos/PPAs you sometimes need to disable them and/or remove some
packages, but nothing can't be solved by a few apt/yum/dnf commands.

Most of my Debian/Ubuntu servers only need to be installed once when we
got the hardware, and they are upgraded through several major versions
before being retired. Debian has especially well written documentation
for each release on how to upgrade from previous versions.

I've about three dozen shared and heavily used Fedora workstations that
haven't been reinstalled since 2012? And we have upgraded them through
each Fedora release using yum/dnf. The only problem I could remember was
when we found that our initial allocation for the /boot partition turned
out to be too small in recent years, when kernels are becoming
monstrous. We simply adjusted the partitions and rsync'ed the whole root
directory from backup. Still didn't do reinstall. These upgrades were
usually done by volunteer student admins following Fedora's
documentation, and few of them complained.

Same can be said for our Ubuntu laptops. In most cases, end user just
needed to click Upgrade when a new major version was released, and most
of them went through without much trouble. Although the new versions
were usually buggy in many ways, it usually wasn't the upgrade process
to be blamed.

However, that can't be said for CentOS/RHEL. You are totally right that
CentOS are better reinstalled/imaged rather than upgraded.