Installing on RAID with Ubiquity [was: Proposal to drop Ubuntu alternate CDs for 12.10]

Martin Pitt martin.pitt at
Tue Aug 28 05:38:39 UTC 2012

Hello Steve,

Steve Langasek [2012-08-27 14:50 -0700]:
>  - RAID is relatively straightforward to turn on post-install.  You install
>    to one disk, boot to the system, assemble a degraded RAID with the other
>    disks, copy your data, reboot to the degraded RAID, and finally merge
>    your install disk into the array.  It's not quick, but it's *possible*.

I got curious and tried it the other way: I used gparted for creating
my partitions, installed mdadm in the live system and used it to build
a /dev/md0, then told Ubiquity to create partitions in that and
install to it. That part worked fine.

After Ubiquity was done, there is some unnecessary "fun" though, which
might still be fixable for Quantal:

 * It would be nice if Ubiquity could install mdadm for me if it sees
   that any of its target partitions are on /dev/md*.

   To do this manually, I tried:

   * mount /dev/md0p1 /target, chroot /target
   * apt-get install mdadm; that fails because /etc/resolv.conf is
     empty, so exit chroot, apt-get download mdadm, copy to
     /target/tmp, chroot again, dpkg -i
   * that fails because it cannot access /dev etc, so back out of the
     chroot, bind-mount /dev/, back into the chroot, dpkg
     --configure -a, get scared by the warnings about not being able
     to load MD suppport

   If ubiquity would install it along with its other setup, these
   would be avoided.

 * After that, booting fails because the generated grub configuration
   hardcodes /dev/md0p1, but initramfs/kernel create it as /dev/md127p1. 
   It would be nice if grub/Ubiquity used UUIDs for the root partition
   as usual; in the initramfs /dev/disks/by-uuid/... exists just fine.

After that, the system boots just fine. I think this approach is still
faster than post-install setup of RAID.

Is it desirable/possible to fix these issues? If so, I'm happy to file
two bugs for these issues.



P.S. +1 from me for dropping Alternates.

Martin Pitt                        |
Ubuntu Developer (  | Debian Developer  (
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