Missing modules (cat /proc/modules; ls dev)ALERT! /dev/md0 does not exist.
There's the culprit. You want the kernel to boot from a device (the RAID array) that doesn't (yet) exist. Possible solution: divide both disks into 2 partitions, sdX1 (small, ca 1 GB) and sdX2. Combine both sdX1 partitions in a RAID1 array and use the rest as RAID0. Use the RAID1 to boot the system. Alternatively, only divide the largest disk and use that partition to boot from, while retaining the rest and the smaller drive for the RAID0 setup.