One of my gifts for Christmas were two 18.3GB SCSI hard drives. These hard drives quickly made it into my 433a DEC alpha box (as the previous SCSI drive was only 4GB and impossible to install anything onto). After some quick installing, the box booted with two brand new (loud) hard drives. Toss in the Gentoo alpha boot CD and I was well on my way to getting yet another Gentoo box up.
Because I didn’t want to figure out a way to split the two drives for partitions, I decided to use them in a RAID. Problem: No RAID card installed. Solution: Software RAID.
(These are just notes for me so I can do this again in the future if I need to)

Probe necessary modules to load the raid devices

modprobe raid1 (For RAID 1)
modprobe raid0 (For RAID 0)

(Although I am using raid0 for speed, I need a raid1 for the boot partition as aboot (the alpha bootloader) does not recognize raids)
Partition the hard drives

fdisk /dev/sda
b (Use a BSD disklabel, not a DOS FDISK)
**Set up the partitions as usual**

Remember: RAID1 for /boot (so it can stay the same size). RAID0 for /swap and / (so keep /swap half the size as it will be spread apart two drives)
Do the same to the /dev/sdb device (same layout!) (shortcut: )

sfdisk -d /dev/sda | sfdisk /dev/sdb

Create the /dev nodes:

mknod /dev/md1 b 9 1
mknod /dev/md2 b 9 2
mknod /dev/md3 b 9 3
mknod /dev/md4 b 9 4

Now create the raid partitions:

mdadm –create –verbose /dev/md1 –level=1 –raid-devices=2 /dev/sda1 /dev/sdb1
mdadm –create –verbose /dev/md2 –level=0 –raid-devices=2 /dev/sda2 /dev/sdb2
mdadm –create –verbose /dev/md3 –level=0 –raid-devices=2 /dev/sda4 /dev/sdb4

Note that because we are using a BSD disklabel, do NOT use /dev/sda3 or /dev/sdb3 (or wherever the c: slice exists). If you assign a node to the c: slice, you will overwrite the entire disk. Refer to your fdisk setup to know where the c: slice is located
–level=1 is RAID1; –level=0 is RAID0
Now save the configuration:

mdadm –detail –scan >> /mnt/gentoo/etc/mdadm.conf

Format and mount the drives as usual..

make.conf notes:

ACCEPT_KEYWORDS=”alpha”
CFLAGS=”-mieee -O2 -mcpu=ev56 -pipe”
CHOST=”alphaev56-unknown-linux-gnu”
CXXFLAGS=”-mieee -O2 -mcpu=ev56 -pipe”

(More notes to come as I progress in the install)

~Jaker

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