Bug#686955: grub-installer: Grub fails to install on dm-crypt on LVM on SATA RAID 0
Dear Lennart,
Thanks very much for such a fast response --- I'm well aware that dmraid
is "not recommended", but it would be really handy if I could keep it
for the Windows dual boot. Your suggestion that mdadm supports Intel
RST sounds really interesting --- but I can't see anything that
documents how you activate/use it in the Debian installer.
It does appear possibly to just be enabled by default, in that if I run
through the wheezy installer *without* adding the dmraid=true kernel
boot parameter, then it recognises a "Linux Software Raid" array on
/dev/md126; with some false starts I've managed to partition this as
before (small /boot, then a large dm-crypt partition on which I put LVM,
then splitting the LVM into swap and root partitions). Again, grub
tries to install to /dev/hda1 and fails, but this time when I reboot to
the wheezy rescue mode, things are much more complicated. During disk
discovery, it doesn't recognise the RAID array until I tell the
installer to look for it, at which point it recognises /dev/md126 but
doesn't do anything with it. I had to manually start a shell and invoke
cryptsetup luksOpen /dev/md126p7 dm-6_crypt
then restart the disk discovery process, finally being given an option
to use /dev/mapper/waif-root for my root partition. Then, however, I
ran into trouble with grub: update-grub complained of file not found
repeatedly, and grub-install failed to install because it "couldn't
find" my LVM root volume. /boot/grub/device.map at this point contains
just three drives, my USB install disk, and the base hard drives of the
machine's RAID array (as hd0, hd1, hd2 respectively). If I add a bogus
(hd3) entry pointing at the raid drive, /dev/md126, then update-grub
stops complaining "file not found", and even successfully finds the
Windows partition. If I then add a bogus (hd4) entry pointing at the
dm-crypt partition I mounted, /dev/mapper/dm-6_crypt, then grub-install
stops complaining about not finding /dev/mapper/waif-root and claims to
have successfully executed.
The net result though, is exactly the same --- on reboot I get
Welcome to GRUB!
error: no such disk.
Entering rescue mode...
grub rescue>
I'm assuming I need some additional magic to make grub assemble the raid
array, find the boot partition, decrypt the dm-crypt partition, and open
the root volume...
Conrad
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