AFAIK in practical terms RAID 1 0 and 0 1 both require a minimum of four drives The semantics of some volume management software is such that constructing nested RAID sets involves combining two or more entities each of which must consist of one or more drives so within those microcosms it would seem theoretically possible to have 1 0 with two drives but not really I suspect that s the source of the confusion Taking that bit out sounds reasonable