Unable to mount root

I've encountered some hairy problems attempting to boot into a raid1
root filesystem.
The boot fails with unable to mount.  The trouble starts with ...
EXT2-fs: md(9.0): couldn't mount because of unsupported optional
features (fff80000).
cramfs: wrong magic
Md: swapper(pid 1) used obsolete MD ioctl, upgrade your software to use
new ictls.
Kernel Panic.

I'm using a straight debian woody with 2.4.18 all raid options compiled
into the kernel.

I use mkraid to create the md0 device with the following raidtab...

## Test RaidTab

raiddev                 /dev/md0
raid-level              1
nr-raid-disks           2
chunk-size              16
# Spare disks for hot reconstruction
nr-spare-disks          0
persistent-superblock   1
device                  /dev/sda1
raid-disk               0
# pseudo failed disk current root part
device                  /dev/hda1
failed-disk             1


Should I be using mdadm instead of mkraid, or are the Debian woody
raidtools too old, too new???

I'm using Raidtools2 version 0.90.200109.

Any help greatly appreciated!

Lewis