Intel software raid disks not detected by alternate installer if in RAID1

[stephen_liu]

11.10 64-bit alternate installer does not detect any disks/partitions when I get to the step after it asks me if I "want to activate the SATA RAID devices". After replying yes, no disks and/or partitions show up.

11.04 64-bit alternate installer works fine.

The 11.10 64-bit LiveCD also works fine but I need the alternate installer for an encrypted installation.

The problem seems to also be described here:
http://askubuntu.com/questions/71466/raid-1-array-not-found-in-server-installer
If this source is correct, apparently the mirroring (ie: RAID1) drivers aren't loaded in the 11.10 kernel. But then why were they loaded in 11.04? Was it purposefully or inadvertently left out?

I'd love to test RAID0 to see if that works but can't wipe this system and don't have another on hand.

[Brian Murray (brian-murray)]

From the askubuntu.com question we see the following:

24 22:46:43 disk-detect: Serial ATA RAID disk(s) detected.
Oct 24 22:46:44 disk-detect: Enabling dmraid support.
Oct 24 22:46:44 kernel: [ 76.836245] device-mapper: table: 253:0: mirror: unknown target type
Oct 24 22:46:44 kernel: [ 76.836248] device-mapper: ioctl: error adding target to table
Oct 24 22:46:44 disk-detect: ERROR:
Oct 24 22:46:44 disk-detect: device-mapper target type "mirror" is not in the kernel
Oct 24 22:46:44 disk-detect:
Oct 24 22:46:44 disk-detect: RAID set "sil_bhbgdgdefacd" was not activated
Oct 24 22:46:44 udevd[9332]: inotify_add_watch(6, /dev/dm-0, 10) failed: No such file or directory
Oct 24 22:46:44 kernel: [ 76.931742] device-mapper: table: 253:0: mirror: unknown target type
Oct 24 22:46:44 kernel: [ 76.931745] device-mapper: ioctl: error adding target to table
Oct 24 22:46:44 disk-detect: ERROR:
Oct 24 22:46:44 disk-detect: device-mapper target type "mirror" is not in the kernel
Oct 24 22:46:44 disk-detect:
Oct 24 22:46:44 disk-detect: RAID set "sil_bhbgdgdefacd" was not activated

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Denis Kozlov (dezlov)]

The same problem also occurs with Ubuntu 12.04 Server 64-bit, confirmed on a physical machine.

Here is a related bug reported:
Bug #961847: installer cannot start 'fakeraid' devices that need dm-mirror or dm-raid modules
https://bugs.launchpad.net/ubuntu/+source/debian-installer/+bug/914536