[CentOS] Disappearing Network Manager config scripts

Thu May 1 18:42:55 UTC 2014
m.roth at 5-cent.us <m.roth at 5-cent.us>

Les Mikesell wrote:
> On Thu, May 1, 2014 at 12:45 PM, Lamar Owen <lowen at pari.edu> wrote:
>> On 05/01/2014 10:56 AM, Steve Clark wrote:
>>> I feel for you then. I guess we have been lucky in the 6 or 7 hardware
>>> platforms we have used that the nics ( minimum 3, usually 4 or more )
>>> have always stayed the same names in the same order.
>> That's actually an illusion.  If the detection pulls it up in a
>> different order, then by MAC address it will get put in the old order,
>> at least with EL6.  Here's a 'grep' excerpt showing the fun:
>> ++++++++++
>> Apr 21 14:39:25 www kernel: udev: renamed network interface eth0 to
>> rename2
>> Apr 21 14:39:25 www kernel: udev: renamed network interface eth1 to
>> rename3
>> Apr 21 14:39:25 www kernel: udev: renamed network interface eth2 to eth0
>> Apr 21 14:39:25 www kernel: udev: renamed network interface eth3 to eth1
>> Apr 21 14:39:25 www kernel: udev: renamed network interface rename3 to
>> eth3
>> Apr 21 14:39:25 www kernel: udev: renamed network interface rename2 to
>> eth2
>> ++++++++++
>
> Yes, the names are nailed down after the first run creates the
> /etc/udev/rules.d/70-persistent-net.rules with the MAC addresses for
> that box.   But the first detection is more or less random.  If you
> pop that disk into a different chassis, if you don't remove that file
> you'll get all new names with higher numbers and if you do remove it
> you get the same names but random ordering again.   And the ifcfg-eth?
> files that also have the MAC address entries will be ignored if the
> names and MACs don't match.

What I do when I upgrade a box via rsync is either rm
70-persistant-net.rules, or look at the MAC addresses beforehand, and edit
the rules so that they're correct for this box before the reboot.

       mark