I have had to install 3 LPARs with Debian on 2 olds IBM P5 Series.
The installation works like a charm but a couple of time, I got buggy screens when I make many changes to disk partitions, excluding that problem, I have no more issues to finish the installation.
The great surprise is in the first boot when I got something like “kernel image not found”, having finished my research, this is a old bug, it can be fixed inside the installation or booting on rescue mode with the installation cd, you have to create the “etc” folder in “/boot” and copy yaboot.conf file.
After you mount all FS on rescue mode:
cp /etc/yaboot.conf /boot/etc/
Now reboot and cross your fingers.