Bug#524342: Problem might be related to raid metadata version
I was able to boot into my system using a kernel off the System Rescue CD. But neither grub-legacy, grub-pc nor lilo was able to install on either the mbr or any partition.
At that time I only had two partitions on all three drives. One was softraid1/root and the other softraid1/swap. I believe that problem is related to the new metadata version in mdadm (1.2) as pointed out over here:
But in that bug report they are talking about older versions of Grub2 (prior 1.98+20100720-1), but I even installed from sid ((1.98+20100804-5) and Grub only gave me segmentation faults.
Then I changed my disk layout during install. This time I created a boot partition on /dev/sda with ext3, no softraid, no mdadm and put root into a softraid (metdata 1.2, created by squeeze install) over all three drives. The softraid partitions start about 1GB into the drives. There is the boot partition up front. I was not able to install grub on the drive, but I was able to install Lilo from the installation system. After that I booted into the installation and tried to install Grub again on the MBR, but even though I had a simple boot partition that Lilo was able to boot from I got a segfault from both Grub-legacy and Grub-PC trying to install those. On any of the mbrs from the three disks as well as the boot partition.
Meanwhile Lenny installs fine with any setup. But Lenny creates softraid partitions with the 0.9 version metadata.