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I have just replaced a new Supermicro motherboard with another of the same model. Both motherboards appear identical. Both have dual dedicated ethernet ports running off an Intel chipset.

The first board failed with a problem but had a full running copy of Ubuntu Server (64bit) installed. Until it failed it worked well. Now, with the replacement board everything loads and runs as expected but the network drivers never load -- there were no changes made to the OS going to the replacement board.

The system runs off a large RAID array that contains many, many terrabytes of data.

The array controller was pulled from the chassis and a single test drive installed on the replacement motherboard. A new copy of Ubuntu server was then installed to make certain the ethernet ports were fully functional. The new install found the ethernet ports correctly and all went well -- the ethernet ports obviously work with a vanilla Ubuntu install (as was the case with the original board).

But the ports still won't work if booted from the original install on the array.

Is there anyone who can suggest a fix?

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Have you compared lsmod from the vanilla install with the corresponding from the original install? – Andreas Aug 21 '10 at 8:23
Can you confirm that it's the drivers that are not loading (compare lsmod output as Andreas says), as opposed to a problem in your network setup? What does ifconfig -a show? What happens if you lsmod the driver manually? Does anything about the Ethernet chipset appear in the kernel logs? – Gilles Aug 21 '10 at 10:31
Check if BIOS versions are the same. – AndrejaKo Aug 21 '10 at 10:56

Check the output of 'dmesg | grep eth'. Also look at /etc/udev/rules.d/70-persistent-net.rules'. The ports are likely now eth2 and eth3 instead of eth0 and eth1. You can remove or edit the udev rules file to reset their ids.

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