Reassociating MAC addresses to ethX after a MAC change
I'm running logical partitions (kind of like VM's) on a Hitachi CB500 blade chassis. I have to make a change to the blade that will regenerate new MAC id's for the six network interfaces (eth0-eth5). Therefore, each ethx device will get a new MAC. Each of these eth devices is bonded. So I have six eth devices and three bonded devices. My concern is being able to reassociate the correct devices to each other after the MAC's change. When I make the change, I assume that new entries will be added to /etc/udev/rules.d/70-persistent-net.rules. Since there is already an entry for eth0, it could likely call it eth6 (the next available eth device name available) and give it a new MAC. As I'm managing six different devices, it seems to me that I'll reboot to find eth6-eth11 entries, all with new MAC's and new eth numbers and I won't know which entry (from eth6-eth11) to rename back to eth0. Which device is really eth0? Anyone dealt with this before?
Responses
Red Hat
Guru
7257 points
What RHEL version is this? I assume RHEL6, if so:
Move your 70-persistent-net.rules somewhere else before the change, ensure your ifcfg-eth* do not have HWADDR in them. You don't need HWADDR on RHEL6.
udev will see the new MACs as "new" devices, create 70-persistent-net.rules with eth0-eth5, and the existing ifcfg-eth* files will just work.
The only thing which could trip you up is devices enumerating in a different order, so say the old eth0 becomes eth1 and something else becomes eth0. In that case, you'd just edit 70-persistent-net.rules to assign the correct MACs to the correct device names and reboot.
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