[CentOS] upgrading from CentOS 7 to 8

Tue Oct 1 17:57:19 UTC 2019
MAILIST <mailist at toolz.com>

> 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.

When a new major version of any o/s is released, I have found it best
to save what application data I can, delete all partitions on the target
boot disk, and then install from scratch.

I learned years ago to keep application data out of system directories,
ideally on a separate drive that can be mounted on the new installation.
Yes, you do loose your settings, but that's why it would be wise to stick
with the defaults, if possible.  Yes, the database is always in a system
directory by default, so that's why you do a dump before the upgrade.
My "cheat-sheet" of things to do during an upgrade is about 10 pages long.

If you do have to restore from a backup, be sure you do not restore any
system directories (like /etc/fstab).  I made this mistake, once!

System admins must learn to bite the bullet on this part of their job.

Todd Merriman