I've also had the same issue, but with smaller disks: WD RE3 250GB (WD2502ABYS)
Using the suggested sizes when creating the md* devices (a single ext3 / partition + one swap partition) resulted with the "Invalid argument" error message and the initramfs prompt.
Manually defining the size to be slightly less than the suggested size worked like a charm.
I've also had the same issue, but with smaller disks: WD RE3 250GB (WD2502ABYS)
Using the suggested sizes when creating the md* devices (a single ext3 / partition + one swap partition) resulted with the "Invalid argument" error message and the initramfs prompt.
Manually defining the size to be slightly less than the suggested size worked like a charm.
Stu