I will be working off one external HD, and every once in a while will want to make a copy of that external HD to another external HD. What is the best, most efficient way to do this? Something better than dragging and dropping ALL the 400 GB or so of files, when all I really have to do is update it. I have SuperDuper (use it to clone my MBP HD). I could use this, then follow up the initial copy with Smart Updates. Is there an easier or better way? Thank in advance.

I think SuperDuper! and smart updates are an excellent choice for keeping your external drives in sync. Some people would look at this and say that a mirrored RAID setup would be easier. However, real-time sync causes real-time data corruption when you make a mistake. I think there is an advantage to delaying the write to the second drive until you're truly ready to overwrite the files.

Are you also using Time Machine?

Thanks, Michael. Yes, I am using Time Machine to back up my iMac and MBP to a Time Capsule. Why do you ask?

I ask because I think that two external drives would be better utilized by combining Time Machine and SuperDuper! than by simply cloning SuperDuper! drives. It sounds like you have it covered.

I see, I think. Just to be clear, this external HD I am cloning to another external HD has nothing to do with my internal HD. It is just a large group of video files, the contents of which change over time, that I want to keep backed up from one external to another.

The best way perhaps is you to make a archive of your old files and backup the another external drive. It generally will be faster and won't eat up a lot of your CPU time when you do that.

I do that always if I want to make a backup for my MAC.

Hopes that help