Sorry, "yum upgrade" doesn't upgrade the OS, not even from one
version of SL5 to another.  The "yum" man page says:

	upgrade
        Is the same as the update command with the --obsoletes flag set. See update for more details.

An upgrade starts by using rpm to get the version of yum
needed for the version of SL for the upgrade.  See
https://www.scientificlinux.org/documentation/howto/upgrade.5x

Jon

On Tue, Jul 23, 2013 at 04:15:12PM -0700, Yasha Karant wrote:
> Will "yum upgrade" upgrade in place only the applications/files that
> come stock with SL without touching existing partitions or systems
> configuration folders (e.g., network information, password, shadow,
> and the like)?
> 
> I was repeatedly told on both this and the CentOS list that TUV
> configuration no longer permitted this sort of operation (at one
> time, TUV provided production -- not just Fedora "beta" -- binaries,
> and during that epoch, the TUV installer had an "upgrade" option).
> 
> Yasha Karant
> 
> On 07/23/2013 04:02 PM, g wrote:
> >hello pat,
> >
> >On 07/23/2013 01:17 PM, Pat Riehecky wrote:
> >>It is not possible to upgrade from the 5x branch to the 6x branch.  A
> >>fresh
> >>install is required.
> >>
> >>Pat
> >
> >i have to disagree with you on this issue.
> >
> >iirc, my last 5x was 5.9. i first ran "yum update" and then ran "yum
> >upgrade",
> >both ran with out any problems.
> >
> >my /etc/reddhat-release shows;
> >
> >     Scientific Linux release 6.3 (Carbon)
> >
> >
> >i did not check to insure that all packages are now at 6.3, but i would
> >presume that they are.
> >
> >
>