Comment 3 for bug 1423605

So we discovered a workaround for this.

It turns out that disks had fakeraid superblocks. When d-i or curtin go to install, they are getting screwed up by this.

So, our solution was to boot the servers with an Ubuntu livecd. We used https://help.ubuntu.com/community/Installation/MinimalCD

Proceed into rescue mode, run through the prompts, and execute a shell.

From the shell prompt. You'll want to stop all md devices. *(please forgive the freehand scripting), and then run mdadm --zero-superblock /dev/sd* on the remaining disk drives.
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#!/bin/bash
for i in `ls /dev/md*`; do
mdadm --stop $i
done

for i in `ls /dev/sd*`; do
mdadm --zero-superblock $i
done

That should do it.
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It would be nice if we fix curtin to detect errant superblocks, and possibly clear them. It might also be nice to be able to select some sort of fakeraid functionality from maas for each machine. I haven't fully thought this through, and I'll leave that up to the maas team to sort out.