Ah, I see you've updated the question: > Do you need DSM to rebuild? I don't think so. I've never had to do it without DSM, but since it is just mdadm and lvm

Ah, I see you've updated the question: > Do you need DSM to rebuild? I don't think so. I've never had to do it without DSM, but since it is just mdadm and lvm you should be able to connect all the remaining disks to and Linux box and run the appropriate mdadm commands to fix the array.