dmraid/lvm installation troubles

[David Abrahams]

I've been having trouble finding accurate information about this on
the web.

I recently acquired a 2xdual-core opteron system based on Tyan's K8WE
motherboard, which has NVidia nForce4 RAID support.  I tried for days
to set up a working ubuntu system with dmraid and LVM.  I want to be
conservative about data security, and the combination of LVM + RAID 1
seems to provide me with the best of all possible worlds.

I think I may have gotten pretty close, but no cigar so far.  There
are a number of sites that claim to have instructions for doing such
an installation, but none of the instructions work out-of-the-box for
me.  I've also seen claims that Fedora Core 5 supports installation
onto a dmraid array, but also lots of postings from people for whom it
has failed.

http://www.ubuntuforums.org/showthread.php?t=194455 describes what
I've been doing.  I think input is needed from someone who really
understands the device mapper, dmraid, and LVM, and as far as I can
tell, this is where all those people hang out.  If someone would be
willing to help me understand this problem I'll happily put up a
webpage that explains all the missing information so nobody has to
pester you about it again ;-)

At this point I have been able to get dmraid installation to complete
without error, but only twice.  I tried to reproduce the first method
and it failed in exactly the way described.  The second method
involved rebooting from the live CD, reconstructing the LVM partions
into a filesystem, chrooting, and then doing another apt-get install.
Haven't tried to reproduce that method yet.

Anyway, at this point I have grub starting the safe-mode boot
sequence, but it fails at the point of having mounted the root
filesytem at /root.  Apparently all that's there is one file:
lost+found. In fact, at that point in the boot sequence, that holds
true for all the LVM partitions.  The /boot partition is a primary
ext3 partition.  That may be overly conservative, but at least it was
clear to me that it would be reachable that way :)

Note: I am currently setting this system up for multiboot, although
eventually I plan to run Windows virtualized (e.g. under VMWare or
Win4Lin).  As I understand it, mdadm might be easier to set up but is
not compatible with dual-booting into windows; is that right?

Note2: In fact it may be a few days before I can work on this again;
the machine has some minor hardware problems and it's going back to
the manufacturer for repair.  That said, I think I can still learn a
lot in the meantime.

Thanks in advance for any assistance you can offer,

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com