This document should show the long process for setting up a kernel-based software RAID system on OpenBSD 3.2 with the root partition / on a raid0a device, swap and /tmp on raid1b and raid1d, and /var and /usr on raid2e and raid2f. This project utilizes raidctl.

From the man raidctl(8):

raidctl is the user-land control program for raid(4), the RAIDframe disk device. raidctl is primarily used to dynamically configure and unconfigure RAIDframe disk devices. For more information about the RAIDframe disk device, see raid(4).

This document assumes the reader has at least rudimentary knowledge of RAID and RAID concepts.

The sample system has sd0(18gb), sd1(18gb), and sd2. I made a complete install of OpenBSD 3.2 on sd2. References:

raidctl(8)
installboot(8)
http://marc.theaimsgroup.com/?l=openbsd-misc&m=103635776223483&w=2
http://marc.theaimsgroup.com/?l=openbsd-misc&m=102839903925282&w=2
http://archives.neohapsis.com/archives/openbsd/2001-10/0142.html

http://www.blackant.net/other/docs/howto-full-system-mfs.php

-- modify the kernel:

# add
option		RAID_AUTOCONFIG
option		NMBCLUSTERS=8192
option		BUFCACHEPERCENT=15 # default is 5
option		DUMMY_NOPS	# speed hack; recommended
pseudo-device	raid		4	# RAIDframe disk driver

-- make partitions RAID

%disklabel -E sd0
# /dev/rsd0c:
type: SCSI
disk: SCSI disk
label: DK32DJ-18MC    
flags:
bytes/sector: 512
sectors/track: 447
tracks/cylinder: 3
sectors/cylinder: 1341
cylinders: 26866
total sectors: 36102720
rpm: 3600
interleave: 1
trackskew: 0
cylinderskew: 0
headswitch: 0		# microseconds
track-to-track seek: 0	# microseconds
drivedata: 0 

16 partitions:
#        size   offset    fstype   [fsize bsize   cpg]
  a:   307026       63    4.2BSD     1024  8192    16 	# (Cyl.    0*-
228)
  c: 36102720        0    unused        0     0       	# (Cyl.    0 -
26922*)
  d:   409005   307089      RAID                      	# (Cyl.  229 -
533)
  e:  5767641   716094      RAID                      	# (Cyl.  534 -
4834)
  f: 29614320  6483735      RAID                      	# (Cyl. 4835 -
26918*)

% disklabel -E sd1
# /dev/rsd1c:
type: SCSI
disk: SCSI disk
label: DK32DJ-18MC    
flags:
bytes/sector: 512
sectors/track: 447
tracks/cylinder: 3
sectors/cylinder: 1341
cylinders: 26866
total sectors: 36102720
rpm: 3600
interleave: 1
trackskew: 0
cylinderskew: 0
headswitch: 0		# microseconds
track-to-track seek: 0	# microseconds
drivedata: 0 

16 partitions:
#        size   offset    fstype   [fsize bsize   cpg]
  a:   307026       63    4.2BSD     1024  8192    16 	# (Cyl.    0*-
228)
  c: 36102720        0    unused        0     0       	# (Cyl.    0 -
26922*)
  d:   409005   307089      RAID                      	# (Cyl.  229 -
533)
  e:  5767641   716094      RAID                      	# (Cyl.  534 -
4834)
  f: 29614320  6483735      RAID                      	# (Cyl. 4835 -
26918*)

-- create /etc/raid0.conf:
START array
1 2 0
START disks
/dev/sd0d
/dev/sd1d
START layout
128 1 1 1
START queue
fifo 100

-- create /etc/raid1.conf:
START array
1 2 0
START disks
/dev/sd0e
/dev/sd1e
START layout
64 1 1 0
START queue
fifo 100

-- create /etc/raid2.conf:
START array
1 2 0
START disks
/dev/sd0f
/dev/sd1f
START layout
128 1 1 1
START queue
fifo 100

-- configure raid arrays
raidctl -C /etc/raid0.conf raid0
raid -I 135790 raid0
raid -i raid0
disklabel -E raid0
# /dev/rraid0c:
type: RAID
disk: raid
label: fictitious
flags:
bytes/sector: 512
sectors/track: 128
tracks/cylinder: 8
sectors/cylinder: 1024
cylinders: 399
total sectors: 408832
rpm: 3600
interleave: 1
trackskew: 0
cylinderskew: 0
headswitch: 0		# microseconds
track-to-track seek: 0	# microseconds
drivedata: 0 

16 partitions:
#        size   offset    fstype   [fsize bsize   cpg]
  a:   408832        0    4.2BSD     8192 65536    32 	# (Cyl.    0 -
399*)
  c:   408832        0    unused        0     0       	# (Cyl.    0 -
399*)


newfs /dev/rraid0a
mkdir /mnt/kernel0
mkdir /mnt/kernel1
mount /dev/raid0a /mnt
mkdir /mnt/etc
mkdir /mnt/dev
mkdir /mnt/bin
mkdir /mnt/sbin
cd /etc
tar cXf - . | tar -xpf - -C /mnt/etc
cd /bin
tar cXf - . | tar -xpf - -C /mnt/bin
cd /sbin
tar cXf - . | tar -xpf - -C /mnt/sbin
cd /dev
tar cXf - . | tar -xpf - -C /mnt/dev
mkdir /mnt/tmp
mkdir /mnt/usr
mkdir /mnt/var
cp -r .cshrc .profile bsd bsd.old boot stand altroot root /mnt

newfs /dev/rsd0a
newfs /dev/rsd1a
mount /dev/sd0a /mnt/kernel0
mount /dev/sd1a /mnt/kernel1
cp /bsd /bsd.old /boot /mnt/kernel0
cp /bsd /bsd.old /boot /mnt/kernel1

raidctl -C /etc/raid1.conf raid1
raid -I 246810 raid1
raid -i raid1
disklabel -E raid1
# /dev/rraid1c:
type: RAID
disk: raid
label: fictitious
flags:
bytes/sector: 512
sectors/track: 128
tracks/cylinder: 8
sectors/cylinder: 1024
cylinders: 11264
total sectors: 11535104
rpm: 3600
interleave: 1
trackskew: 0
cylinderskew: 0
headswitch: 0		# microseconds
track-to-track seek: 0	# microseconds
drivedata: 0 

16 partitions:
#        size   offset    fstype   [fsize bsize   cpg]
  b:  8388608        0      swap                      	# (Cyl.    0 -
8191)
  c: 11535104        0    unused        0     0       	# (Cyl.    0 -
11264*)
  d:  3146496  8388608    4.2BSD     8192 65536    32 	# (Cyl. 8192 -
11264*)


newfs /dev/rraid1d

raidctl -C /etc/raid2.conf raid2
raid -I 123456 raid2
raid -i raid2
disklabel -E raid2
# /dev/rraid2c:
type: RAID
disk: raid
label: fictitious
flags:
bytes/sector: 512
sectors/track: 128
tracks/cylinder: 8
sectors/cylinder: 1024
cylinders: 28920
total sectors: 29614208
rpm: 3600
interleave: 1
trackskew: 0
cylinderskew: 0
headswitch: 0		# microseconds
track-to-track seek: 0	# microseconds
drivedata: 0 

16 partitions:
#        size   offset    fstype   [fsize bsize   cpg]
  c: 29614208        0    unused        0     0       	# (Cyl.    0 -
28920*)
  e: 25165824        0    4.2BSD     8192 65536    32 	# (Cyl.    0 -
24575)
  f:  4448384 25165824    4.2BSD     8192 65536    32 	# (Cyl. 24576 -
28920*)


newfs /dev/rraid2e
newfs /dev/rraid2f
mkdir /mnt2
mount /dev/raid2e /mnt2
mkdir /mnt2
cd /var
tar -cXf - . | tar -xpf - -C /mnt2
mkdir /mnt3
mount /dev/raid2f /mnt3
mkdir /mnt3
cd /usr
tar -cXf - . | tar -xpf - -C /mnt3

cd /usr/mdec
./installboot -v /mnt/kernel0/boot ./biosboot sd0
./installboot -v /mnt/kernel1/boot ./biosboot sd1

raidctl -A root raid0
raidctl -A yes raid1
raidctl -A yes raid2

-- modify /mnt/etc/fstab
/dev/raid0a / ffs rw 1 1
/dev/raid1b none swap sw 0 0
/dev/sd2h /home ffs rw,nodev,nosuid,softdep 1 2
/dev/raid1d /tmp ffs rw,nodev,nosuid,softdep 1 2
/dev/raid2f /usr ffs rw,nodev,softdep 1 2
/dev/raid2e /var ffs rw,nodev,nosuid,softdep 1 2

After you reboot, be sure to delete the raid config files from /etc because you'll get "Device already configured!" errors otherwise. The errors don't hurt anything, but they definately aren't needed. The raidctl -A yes raid1 lines eliminate the necessity of having the raid configuration files in /etc.