[rhelv6-list] RHEL 6.4 udev just butchered my ethernet device names!

[Red Hat Enterprise Linux 6 (Santiago) discussion mailing-list]

Red Hat Enterprise Linux 6 (Santiago) discussion mailing-list
<rhelv6-list at redhat.com> wrote:
> Reading through the RHEL 6.4 tech notes, stumbled across this in
> Chapter 4.1 (known issues):
>
>   kernel component
>     Recent Red Hat Enterprise Linux 6 releases use a new naming scheme for
>     network interfaces on some machines. As a result, the installer may
>     use different names during an upgrade in certain scenarios (typically
>     em 1 is used instead of eth0 on new Dell machines). However,
>     the previously used network interface names are preserved on the
>     system and the upgraded system will still use the previously used
>     interfaces. This is not the case for Yum upgrades.

I looked through the notes, but missed it, especially that last statement ...
  "This is not the case for Yum upgrades"

Which was preceded by ...
  "the previously used network interface names are preserved on the
   system and the upgraded system will still use the previously used
   interfaces."

> .. so using the install media to upgrade preserves device names, but on
> *some* machines upgrading using yum will clobber device names.

To put it technically (if I'm understanding this correctly) ...
 - Anaconda (off-line upgrade) is preserving the names
 - YUM (on-line upgrade) is not, at least for some OEM hardware

> Known issue, but no bugzilla entry cited.

I'm going to look up the "biosdevname" and related package BZs and get
the full story, if there is one.

I know upstream Fedora switched to the new nomenclature awhile back
(and "biodevname" does seem to be installed on all of my Fedora
systems).  But as I mentioned before, RHEL6 does not, and I'm ignorant
of the logic whenever it may (Customer opt-in?  Anaconda detection of
select OEM hardware?  Other?).

Precision (expected results) is what I'm looking to explain, at least
for myself.

> It would have been nice if they pointed to a more detailed description
> of how & when this happens.

Well, the OEMs and their BIOSes are involved here.  There is likely a
bigger story to this.  I also use Cobbler, although I'd be interested
to know if that is causing any deployment issues for those leveraging
biosdevname (since I have not been).

Again, my prior ignorance, I thought it wasn't going to be enabled (at
least by default) until RHEL7, as I had never seen it on 6.2 or 6.3
with many bare metal solutions, including IBM Blades.  But I haven't
had brought hardware exposure as of late, and definitely not Dell in
any recent years.  In fact, that's entirely why I read the OP
information incorrectly (i.e., I thought they switched to the
biosdevnames, when it was they switched back from the biosdevnames
after upgrading to 6.4).

-- bjs

P.S.  This will be my last post on-list.  I will just respond to just
those who inquire off-list.