[CentOS] Disappearing Network Manager config scripts

[Steve Clark]

On 05/01/2014 09:09 AM, Les Mikesell wrote:
> On Thu, May 1, 2014 at 5:54 AM, Steve Clark <sclark at netwolves.com> wrote:
>> On 04/30/2014 02:41 PM, Les Mikesell wrote:
>>
>> On Wed, Apr 30, 2014 at 1:28 PM, Steve Clark <sclark at netwolves.com> wrote:
>>
>> So, have you ever had to deal with a CentOS box and multiple NICs.
>> Especially one where you've cloned it or moved a disk to a new
>> chassis?   Apparently there is just not a good way to identify
>> interfaces.
>>
>> Yep, do it all the time - first two thing I do are:
>> rm -f /etc/udev/rules.d/70-persistent-net.rules
>> rm -r /etc/sysconfig/network-scripts/ifcfg-eth*
>> and then reboot.
>>
>> So, now you've got 6 NICs connected to 6 different switches.  Which
>> name is which?  This is a really fun exercise when the box is remote
>> and you are trying to tell someone used to configuring windows systems
>> how to get it to a point where you can ssh in.
>>
>> I guess I am confused, you haven't ever worked with the hardware you are
>> installing the cloned
>> drive in? If that is true then I guess you have a problem.
>>
> "Working with it" doesn't matter.  And network manager or not doesn't
> matter.  Interfaces get named in a random order unless it is a Dell
> with the netbios naming scheme and probably then only for the
> motherboard NICs.   Our servers generally have on-board Broadcomm and
> Intel cards and the names within a set may stay ordered, but the cards
> and motherboards will flip randomly if there are not already matching
> items with the correct MAC addresses in the udev rulss file (in 6.x,
> in 5.x having a matching MAC in the ifcfg-eth? file was enough to
> rename the device to match).   This is just a response to your comment
> about windows names being difficult to know, (and a long-standing
> problem on its own) and doesn't relate much to the NetworkManager
> discussion.   If you only have one (or maybe even a pair on the
> motherboard or a single card) you might always see the same ordering -
> if so consider yourself lucky because that is not the general case.
> We usually have to run through a drill like 'ip link ls' to get a list
> of interface names,  then iterate through them with 'ifconfig up' and
> use ethtool to see which has link up, connecting one at a time.    So,
> in my opinion, there are problems with the old system that need to be
> fixed, but they aren't the things that networkmanager does.  A way to
> restore a backup to an identical machine and have the same NICs in the
> same positions get the old configurations would be nice.  Or at least
> to know the names of the NICs in the same positions.  (And if you go
> back to CentOS3 they did - detection was single threaded back then and
> would always probe in the same order).
>
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.



-- 
Stephen Clark
*NetWolves Managed Services, LLC.*
Director of Technology
Phone: 813-579-3200
Fax: 813-882-0209
Email: steve.clark at netwolves.com
http://www.netwolves.com