[dnanian]

I didn't suggest that you should use an AntiVirus program. I asked whether you were, since AntiVirus programs will take temporary space while copies are being made as they scan the files.

The people who you asked, who pointed at SuperDuper!, are not correct - we do not take temporary space on the source drive while we copy. That's why I'm pointing at other potential areas... perhaps you could run Grand Perspective when the space taken is larger than expected to see what that space actually is?