needed to erase internal disk
 

So I tried to do a copy to my internal disk from a backup, and it strangely kept giving me errors without completing. The error said something to the effect that there wasn't enough disk space. So I finally just used Disk Utility to erase the whole internal disk, and then the copy from my backup went without a hitch. What happened? Why would a SuperDuper copy find itself without enough room? (The disk that the backup was made from had plenty of extra room.) SuperDuper is supposed to be replacing what was on the disk with what is in the backup for that disk.

Without the details, sent with the "Send to shirt pocket" button, it's hard to be sure, but this is quite likely covered in the Troubleshooting section of the User's Guide.

Remember - Smart Delete will only run if it knows how much space it needs to recover...attribute copies don't know, and that can give disk full errors.

Well, maybe my mistake was that I just reflexively used Smart Update, instead of asking that the internal disk be erased first. Does Smart Update require more space than and Erase-then-copy? I've copied back from a backup before without dong that, though. So something was different this time.

Smart Update acts "on encounter" - it walks the drive and does what it's supposed to do at that moment. It doesn't "pre-delete" files.

So, if you (for example) rename a large folder, and we hit the "new" name before the old, we'll copy the new data before deleting the old. That can fill the drive.

Smart Delete will typically "note" this situation and, when we run out of space and know how much space we need, it'll look ahead and free up that amount of space so the operation will succeed. (There's a whole blog post about this - https://www.shirt-pocket.com/blog/in.../smarty_pants/ - that you might find worth reading along with the Troubleshooting section.)

Thank you. So I think the answer is that, yes, when doing a restoration, always do it in Erase, then Copy mode.

That isn't what I said, no.

Well, I guess I'm confused. When I tried to do a restore using Smart Update, it failed repeatedly, for lack of space. That happened with different copies. But when I did it with Erase-then-Copy, it worked.

That's because you encountered the situation described, not because it doesn't work in "normal" situations.

Well, SuperDuper is great for making backups, but one has to have confidence that once a backup is made, restoration can be achieved with them seamlessly. That wasn't the case for me this last time. I do the latter very rarely, so I don't have a lot of practice doing it.

Sure. But there are always cases where a restoration (or even a backup) might have challenges. That's why I'm here, and why the Troubleshooting section of the User's Guide exists.