[CentOS] Editing udev rules Was: More on Re: Really changing the hostname

[Les Mikesell]

On Sat, Feb 16, 2013 at 7:06 AM,  <me at tdiehl.org> wrote:
>>>
>>> I did not even know about this "problem" until I read about it on this list.
>>
>>> From what I've seen, the ports on a single card will be detected in
>> the same order every time.   The issue is that if you have some
>> motherboard NICs and one or more  pci cards, the  order of detection
>> of the groups will be a matter of chance.   Our servers mostly have
>> some Broadcomm's on the MB plus a few multi-port Intel cards.   If you
>> remove the udev rules,  there is no way to know whether the MB NICs or
>> the add-ons will be eth0 and eth1.
>
> Agreed, I have seen that behavior but I was talking about what happens if you
> change a card, put the new MAC address in ifcfg-eth* and do nothing with the
> udev rules.

Under CentOS5 that was sufficient to rename the interfaces to match.
In CentOS6, the names are set in the udev rules and the ifcfg-eth*
files are skipped if the MAC addresses don't match for the names set
by udev.

> I always use ks to build the machines and the interfaces are pre-defined in the
> ks setup.

It works if - and only if - your ifcfg-eth? names match the order that
get set in udev.   If you have multiple cards or different NIC types,
that order isn't predictable.

> I am beginning to believe that. I guess some more research is in order.

You can nail it down if you create the udev rule yourself.

-- 
  Les Mikesell
      lesmikesell at gmail.com