If these drives are IDE (esp if connect via exp card) you might have to set them up first using major/minor inodes -- this only applies if you can't mount them -- IF YOU CAN MOUNT THEM SKIP THIS PART -- To set them up type 'cat /proc/partitions' it shuld read with 2.6.x kernel major/minor/blocks/name, for ex
'3 2 058086083 hda1'
take the paritions you want, copy the major and minor block numbers and type this in: 'mknod /dev/[NAME] [major] [minor]'
NEXT PART HERE.
assuming the first partition is /dev/hda1 and the second is /dev/hdb1 and you want a linear array:
apt-get update & apt-get install raidtools & hdparm -d1 /dev/hda1 /dev/hdb1; #get raid tools and turn on DMA or be forever slow
edit /etc/raidtab with your favorite text editor (vim!) make it read: (you should have a folder /dev/md0)
issue command "mkraid /dev/md0" done;