[dnanian]

OK, I think you've misunderstood what the Sandbox is for. It's not a backup. Like its name, it's a "Safe place to play" -- but you have to start up from it to use it.

It does not substitute for a real backup, because it doesn't contain your user files, and won't even start properly if your real drive isn't there.

So -- the Sandbox is great when you want to start from it to (for example) test out a software update. But, if you want a bootable backup, you need to use "Backup - all files".