Hello all, I will give you a quick description of my set up and then ask the question. I have an iMac, A pro, a mini and a PC on my home network. Airport extreme as my router. I have a 500Gb external plugged into the extreme with the USB and the iMac set up to time machine to the 500Gb external. What I would like to do is add a second external that I have lying around to the USB on the extreme and use both of them to back up one machine… The iMac. The iMac had a 1Tb drive in it and as it gets filled up the single external I am currently using is not going to be enough… But I cannot figure out how to use two externals to back up one HDD in the computer. I did not want to run out and buy another external to handle the load of the 1Tb HDD. I was hoping to use the combination of what I have already. Can this be done with raid or some other type of hard drive configuration tool? Thanks, JT.