Here's my story...
I've always liked Slackware, but getting software raid arrays configured seemed confusing to me, installing the system first on a single hard drive, and then setting up arrays. I have 5 disks (sda through sde). I wanted to set up 2 disks with raid1 containing swapspace and root filesystem, and the other 3 as raid 5 containing /home. I decided to see if it would be easier to install with a different distro.
OpenSuse looked like it would be easy, but after setting everything up with YaSt and installing the whole thing, grub failed to find /boot. I gave up easily because YaSt is just too "friendly" for me.
So I discovered someone's easy-to-follow instructions to set up raid on Gentoo.
I started the gentoo installation process according to those instructions. The following steps were the important ones needed in order to create the arrays:
I inserted the "minimal" gentoo install disk, using the gentoo-nofb kernel:
Using cfdisk I created identical "mirrored" partitions (2 each) on /dev/sda and /dev/sdb for swap and /. Then I single-partitioned /dev/sdc, /dev/sdd and /dev/sde, designating all 7 partitions as "Raid Autodetect."
mknod /dev/md0 b 9 0
mknod /dev/md1 b 9 1
mknod /dev/md2 b 9 2
mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sda1 /dev/sdb1
mdadm --create /dev/md1 --level=1 --raid-devices=2 /dev/sda2 /dev/sdb2
mdadm --create /dev/md2 --level=5 --raid-devices=3 /dev/sdc1 /dev/sdd1 /dev/sde1
Sometime after I got past this point I ran into some snags with the rest of the gentoo install. I could have finished it eventually but I was a little frustrated and took a break.
By some stroke of fortune I then put the Slackware 11.0 install disk in and rebooted. Guess what... Slackware setup recognized the arrays I had configured and very handily installed swap on md1, / on md0, and /home on md2. Auto-setup lilo on MBR and everything worked great. ...so easy!!!