[CentOS] Upgrading to CentOS 6

Tue Feb 25 17:02:11 UTC 2014
Les Mikesell <lesmikesell at gmail.com>

On Tue, Feb 25, 2014 at 10:25 AM, Styma, Robert E (Robert)
<robert.styma at alcatel-lucent.com> wrote:
> I recently built a CentOS 6 system as my main machine at home.
> With a bit of help from members of this list, it is now working
> better than the machine it replaced (RIP).
> The new machine works so well, that I would like to convert some
> CentOS 5 machines to CentOS6.
> I did some research on the web and the new install is still considered
> the proper way to upgrade CentOS.  Same as Fedora and RHEL.
> The question becomes, "What makes the Ubuntu developers so
> clever that they can do major upgrades through their apt based
> update system?"
> There must be some sort of gotcha or tradeoff involved in allowing this.
> Does anyone have any insights on why they can get away with this
> while CentOS cannot?

First, CentOS does exactly what RHEL does, so this is not really a
CentOS question.

The tradeoff is that Ubuntu doesn't go to the effort to ensure that
for 7+ years you can do updates and not have anything that was
previously working break because a change from the update.
RHEL/CentOS may not be perfect at this, but breakage  is very, very
rare because the updates are mostly backported security/bug fixes that
don't change behavior.    Ubuntu does more frequent updates of the
included package versions (even with their LTS version) and if a
package changes behavior that is left as your problem.   By the time
RHEL does it's next major release, you have a many-year jump in the
underlying package versions with enough changes that even if you could
do an automated update it would probably be a bad idea (there may be
things as drastic as new filesytem choices, etc.).   A fresh install
of CentOS isn't difficult and you should have a plan to backup/restore
your own data anyway, so once you get used to the timing it works out
pretty well to match up major releases with  replacing hardware and/or
general cleaning up of your own applications and data.

   Les Mikesell
      lesmikesell at gmail.com