Comment 22 for bug 251164

mdadm is event driven via udev. The special part in the initramfs is the failure hook so that a degraded array will only be activated after a timeout. I'm not sure if we want to auto degrade arrays post boot, but I suppose if we did, we could move that logic from the failure hook to the udev rule.

What confuses me is cryptsetup. I see that there is an upstart job that appears to try and prompt for the password and unlock the device, but as an upstart task, it has no stdin/out, so that prompt can't work. After the system goes multi user you can no longer do a console password prompt. If you want an interactive prompt at that point, you will need something that can interact with the X desktop, and anything that does that obviously isn't going in the initramfs.