root@0[/]# mdadm -A /dev/md0 /dev/sda1 /dev/sdb1
mdadm: /dev/md0 has been started with 2 drives.
root@0[/]# cat /proc/mdstat
Personalities : [raid1]
md0 : active raid1 sda1[0] sdb1[1]
14659200 blocks [2/2] [UU]

unused devices: 
root@0[/]# mount /dev/md0 /mnt/sda1
root@0[/]# ls /mnt/sda1
bin cdrom dev.old firewall home install lilo.conf media opt root sys tmp var
boot dev etc floppy info lib man mnt proc sbin tftpboot usr
root@0[/]#
-----------------------------------------------------

root@0[/]# lilo
Added 2.4.22
Added 2.4.25
Added 2.4.26
Added 2.4.27
Added MemTest
Added 2.6.12.2
Added 2.6.8
Added 2.6.20 *
The Master boot record of  /dev/sda  has been updated.
Warning: /dev/sdb is not on the first disk
The Master boot record of  /dev/sdb  has been updated.
root@0[/]#