I currently have 2 x 1TB WD Caviar Blacks set up in a RAID mirror. I have a separate drive for the OS. What I want to do is install another 2 WD Caviar Greens to increase the RAID to 2TB mirror. However, I'm going to have to set up a RAID 0+1 in order to make it seem like its one single drive... My question is, when I buy the two drives, and try to create this new RAID set up, will I lose my data creating the RAID or will I be fine? The way it is now the 2 x 1TB drives make up a 1TB mirror, but I want to make a 2TB mirror out of 4 x 1TB drives. I'm going to back up the drives anyway, but will I end up having to restore them or will they be fine? Thanks in advance, i hope this made sense!!