On Fri, 6 May 2011, Les Mikesell wrote: herrold:
I'll try to blog about it, but once one knows the 'secret' it is not all that hard to predict -- This unit has three NICs (two onboard of the same type and an addon) which do NOT 'wander around' through reboots
But can you swap the disk into a new chassis of identical hardware and have it come up with the right subnets on the NICs in the corresponding physical positions? Without knowing MAC addresses ahead of time?
Not without prior knowledge of the MAC addresses and edits, but it is still trivial to do. With DHCP fabric on a physical segment, however, the devices will come up and be assigned IPs, the MAC addresses discerned [hooray for 'arpwatch' to make this trivial], and then may be revised into permanent working assignments without the need to resort to ILO or such
Indeed the reason the udev rules segment quoted is in the the rather peculiar order: eth2, eth1, eth0 ... is that I had done just that kind of drive move, and prior to just such edits of that file, it enumerated MAC address and associated them to devices in order: eth0 eth1 eth2 eth3 eth4
I editted the file for the last two [not bothering to move specification stanzas, as udev is indifferent to ordering], and renamed the corresponding /etc/sysconfig/networking-scripts/ifcfg-eth3 and ifcfg-eth4 into eth1 and eth0 respectively. Then within those two files, I edited the DEVICE names to complete the move a disk from the host it was built on, to the host it is now running on
The process is stable and predictable enogh that these edits were done via just such a process, after a 'remote pair of hands' had physiclly installed the drive into a chassis at a datacenter that I cannot presently travel into and work at comfortable, due to an ankle injury some months ago. The 'cold' aisles are too narrow for a stool or chair, and trying to work standing one-legged like a stork is too tiring
-- Russ herrold