We're acting on encounter, pruning on folder exit.

Can't promise "near future". Been in the works for a while...it's a tad tricky, where you can read "tad" as "understatement".

So then isn't my description correct? As it currently works, files would be deleted from destination A and only exist in source B. If they are unreadable/corrupt in source B, the only good copy of the file would have been lost when you pruned destination A. Isn't that the exact same danger you cited?

I know I'm oversimplifying things. I appreciate how difficult proper backup is and that you're taking the time to make sure it works as well as it should.

I'm not trying to argue, so I apologize if it comes across that way. I'm trying to understand better so that I can possibly help myself some with different file management tactics.

No, it's not correct - the order is more randomized (although not really), and it's more likely that the "good" files will be left on the drive (which is why you're running out of space in some situations).

So the same danger does exist, but in far fewer situations instead of possibly every move/rename situation that would happen if you delete first?

I know you're dealing with an insane number of files, but this all makes me think of how Dropbox does deduplication (I think that's the right term). If I move a file, it's not deleted and recopied on the server. I assume though that a local system like that would require a much larger destination drive which would negate the problems I'm having anyway. ;)

Yes - far fewer. And dropbox is a totally different thing, yeah.

Dropbox is working with a tiny number of files in comparison. Sure, we could calculate checksums and compare every file and determine the totally optimal set of operations. And your regular backup would take much, much longer. (Much.)

We have to balance all this stuff. I know it can be frustrating in some rare situations. But those situations are rare, even though they happen to you...

Understood. And again, thanks for taking the time to explain.

Dave, it's Friday, September 13, 2013, and I already did my Mac OS 10.8.4 to 10.8.5 Upgrade!

Thus far I don't see any problems. I will run my usual SD Schedule later today! I assume that it will be a non-event, no problems either!

I assume it's too early to be asking you about the next Mac OS, Mavericks, given your usual NDA Disclaimers! You will probably have some statement about that on your Site's Homepage after that OS is Officially Available, and NDA doesn't apply anymore, right?!

Otherwise, just a Quick Hello and Public Thank You for the SuperDuper = Peace Of Mind!

Should be fine with 10.8.5. And, no - can't comment on Mavericks...

Hiya, Dave!

If you can say, just wondering if you're intending to post Mavericks-related news/announcements on the Shirt Pocket Watch blog?

When the time comes.