Can SL'd disk be backed up over Leopard?

[chexrex]

I recently upgraded my Macbook to Snow Leopard. When I backed it up with SuperDuper to a previous backup (Copy different files), it will not boot anymore. Is it not possible to backup SL over Leopard?

[dnanian]

Not with Copy Different: that cannot be used to make a bootable copy. Use "Smart Update".

[chexrex]

But I always used "Copy Different" before for periodic backups because I wanted to add any new or changed files to my backup disk without removing any files. And it always would boot just fine.

Are you saying that after upgrading to SL, I should have just started a new backup?

[dnanian]

You were lucky. Don't use Copy Newer/Copy Different for a bootable backup. If you must do so, copy only user files to a separate volume that way, and maintain a bootable backup with Smart Update.