If I have a mac pro with two internal hard drives and two external hard drives, is it possible to have time machine back up one internal to one external and one internal to one external Internal A backup to External A, AND Internal B backup to External B. All on one computer. When you enter time machine its all one. I have two internal drives, one is for OSX and all the apps, the other is for itunes only. I want to back them both up to two separate external HDs. Is this possible? Sorry for being confusing.