[CentOS] A question about RAID and partitions

> How do you create several RAID devices if you only have 2 drives?
> Is there a way to create virtual RAID sets?  That sounds too scary.

Well, I may be wrong or may be using the wrong terminology, but on several 
occasions I did create several RAID 0 an 1 partitions on two disks. I would 
create a RAID 0 partition where I needed a boost in performance, a RAID 1 
partition where I needed more security. What do you say is wrong with that? 
Why is it wrong to create RAID devices, even of different types, with only 
two disks? I don't understand what you mean: virtual RAID sets? Of course 
they are virtual, but they are made of real disk space, not the entire disks 
but adequate parts of the disks.