Hi, I have successfully transferred 150GB's of data to an External HD in order to have more available space on the Mac HD. I also have 125GB's of Time Machine Backed Up data on this External HD. However, what confuses me is why there is also another direct copy of 125GB's of Back Ups on the Mac HD yet still. Doesn't the concept of a Back Up require another device (i.e. External HD) to duplicate & transfer the contents from the original (Mac HD)? 1. If the Macbook is already Backed Up on the External HD, why does it still contain a Back Up within itself? (Taking 125GB's of space unnecessarily) 2. How can I delete the Back Up on the Mac HD? or should I not? Would appreciate any help.