Storing my SD data in a .dmg?

[Stray]

I have an external HDD, with two partitions.

The first volume is 60GB (the same size as the HDD on my MacBook Pro). This volume is called "Backup" and it's where my SD images of my system go.

The second volume is called "Extra Space" and it's where my Time Machine backups go. It's also where big videos and .DMG files of programs I've downloaded (like SD!) go, as well as an encrypted .DMG of my sensitive info (bank data, GPG keys, etc.) go.*

The trouble is that whenever I start my Mac, both "Extra Space" and "Backup" are mounted. Now, I almost never use "Backup", except when I'm using SD, so here's what I'm wondering:

1) Can I create a 60GB .DMG and back up my system to that (with SuperDuper!), instead of having a separate volume?
2) Can I make it encrypted and suffer no ill effects?
3) Now the kicker: Can said .DMG still be bootable?

* If you don't do this, you should. Apple has a good walkthrough of creating an encrypted .DMG on their support site. PS: It's a great way to hide your porn!

[dnanian]

No. Image files aren't physical drives and aren't directly bootable.

[Stray]

In that case, is there a way to set it up so that "Backup" is not automatically mounted when the external HDD is connected?

[dnanian]

Not that I know of.

[TMay]

Stray

It's funny you'd mention that....this was a feature of the Mac OS prior to OSX, and some of us have missed it greatly since it disappeared. Progress!!