[systemd-devel] on the default for PredictableNetworkInterfaceNames

[Reindl Harald]

Am 11.04.2016 um 10:40 schrieb Martin Pitt:
> Reindl Harald [2016-04-10 17:44 +0200]:
>>> Because we had a mechanism for stable (but not predictable) interfaces
>>> names, the 75-persistent-net-generator.rules thingy. Without either,
>>> the first time you plugged in a second card/USB dongle/add an ibmveth
>>> etc., chaos would start.
>>
>> that worked perfectly
>
> Hahahahno. :/
>
> It had an inherent race condition of renaming devices to the same
> namespace than the kernel uses (thus creating collisions), and did not
> work at all in virtualized environments (see the long and ever-growing
> MAC blacklist).

on VMware guests with just one NIC it was never a problem
there would be *nothing* to rename and even the udev stuff would not 
have been needed and that first try of "persistent" introduced the 
problem that you have to edit a udev-conf file instead leave the kernel 
in peace

on physical machines with just one NIC ist was never a problem

> Apart from that it had several design problems: it was not predictable
> (names changed across reinstalls), prevented the ability of creating
> one OS image and installing it on many pieces of hardware (as the MAC
> addresses are device specific) and needed constant writability of
> /etc

if you have just one NIC "eth0" ist very predictable
that's the majority of machines

WLAN was alwas "wlan0" and so did not collide and machines with one 
ethernet card and a WLAN card count as "with just one NIC"

in other words: while maintaing a ton of different machines over a 
decade i had not a singel time the problems 
"PredictableNetworkInterfaceNames" are pretending to solve but now i 
have to add for every single install "net.ifnames=0 biosdevname=0" to 
the kernel params which was not needed in the past

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