Comment 4 for bug 1335642

Without really understanding, I tried to hack something and found the following bits, use at your own risk. This is on a degraded mdadm RAID1 with the root filesystem as a LV.

The following procedure was found to help:

  * Interrupt grub and edit the linux command line.
  * Go to the end of the line that starts with "linux".
  * Append "break" to the line.
  * Press "Ctl-X" to boot. You will get a busybox prompt.
  * udevadm trigger --action=add
    * After that, "ls /dev/mapper" shows what is needed for the root parameter: HOST--vg-root
  * exit

The following procedure was found to make the above hack persistent:

  * Add new file /usr/share/initramfs-tools/scripts/init-premount/10hack-raid-udev

#!/bin/sh
sleep 5
udevadm trigger --action=add
exit 0

  * update-initramfs -u