SD doubles Time Machine size?
 

I backed up my "Macintosh HD" with Time machine on an external 500G drive. It took 180G to do that. Then I set up SD to back up all files using Smart update, using that same drive and taking advantage of all that Time machine had copied. The original 180G climbed to 354G, is that to be expected?

thanks in advance,
John

SuperDuper! doesn't "take advantage" of the Time Machine data -- you can't do that, because it's all read-only and allowing it to be bootable would mess it up.

Instead, we ensure it's properly preserved on the drive, so you can store your bootable backup alongside it.

My question really is, if Time machine can back up my 180G with 180G, why does it take SD another 180G to back it up and be bootable. Is this normal? I am asking not criticizing.

Yes; why would it be less?

I guess I am not making my point. If using time machine AND superduper takes up twice as much space as the original data, would it not be better to only use supersuper alone? I started backing up 180G but now after only a few weeks its now taken almost all of my 500G drive to do it. I have another 300G disk drive for photos that I am manually backing up to a 500G drive, and it will be a long time before I will need to upgrade that backup drive.

That depends entirely on why you're using Time Machine, though. If you want to make use of its "historical rollback" capabilities, that's something that SD! won't do. If you just want an up-to-date copy with the ability to recover quickly, we provide that. But they're different, complementary, things...