Disabling RAID autodetection in Ubuntu

Last week I removed two mirrored hard disks from my old home server running Ubunut 6.06 LTS and put them into my new VDR. After that I was not able to boot the server again. It always stopped saying something about “… RAID autodetection …”

So RAID autodetection is a nice feature when you want to have your RAID devices available after booting the system but what if you want to get rid of it? I used an Ubuntu 7.10 alternate CDROM to boot into rescue mode. There I first removed the md device entries from /etc/fstab. But a reboot showed that the system still searched for a RAID and was not able to start. Removing the entries from /etc/mdadm/mdadm.conf did not improve the situation either.

Then I found this Ubuntu forum post recommending deleting the file /usr/share/initramfs-tools/scripts/local-top/md and to update-initramfs. This should work but for me the easiest solution was to run apt-get remove mdadm which updated the initial ramdisk too.