Only use one disk per IDE bus.

Configuring Linux RAID w/ DiskDruid

Add new partitions of type "Linux RAID" (fdisk type "fd")
(You don't specify mount points here).
Make sure that "Allowable Drives" has selected only the disk(s) you want
to create this partition(s) on.

Hit the "Make RAID DEVICE" button to make your mdX device(s).
Select partition type "Linux Native" (the default).
(your boot partition may only be RAID level 1)
Select all of the RAID partitions (created in previous step) which are
to be incorporated into this RAID Metadevice.

Resilver = Rebuild = regenerate mirror/parity data

LEVELS
    0: Stripes and Concatenations  (I think officially only Striping)
        (Linux RAID calls non-striped Concat "Linear mode" and 0? is
        striping.  Striped base partitions should be about same size,
        since the "difference" area will be used linearly not striped).
    1: Mirror without parity or striping
    2: Striping with Hamming-code parity
    3: 2 with dedicated-purpose drives
    4: Just RAID 5 with parity always written to 1 dedicated parity disk.
       (Add disks have parity areas, but all must write to the 1 ded. area).
       Adds bottle-neck on that parity drive.
    5: Block-level striping with distributed parity
       Need 1 parity disk for each 2-X primary parts, each of similar size.
        (Can't use 5 on /, /usr/swap, existing FS)
    6: 5 + 2nd distributed parity
    10: 1 + 0 (stripes)
    SPARES:  Can use spare take-over disks for all but level 0.

RAID 5/6 can survive loss of # of parity dataset counts (so 1 for 5, 2 for 6).