Testing Mojave before upgrading: possible to upgrade a bootable backup?

[neonhallway]

Hi everyone.
I have an older Mac (early 2013 MBP), and I'd like to upgrade to Mojave from Sierra.

My concern is, I've been working on an album of songs for nearly 2 years in Logic, and it would be pure hell if anything messed up those session files, with all their 3rd-party plug-ins, sample libraries and nuances. So I'm trying to think of a conservative way to test the waters before I jump in.

Is it possible to make a bootable clone of my hard drive with Carbon Copy Cloner, and then upgrade the OS only on the backup, while leaving my internal drive on OS 10.12?

If so, I could open those Logic sessions with all my plug-ins still installed, and see if anything breaks before I make any changes to my actual system.

Sorry if this is obvious, but I've never tried it before, and my searches aren't finding anything similar.
Can this be done?

 

[!!!]

Yes, it should be possible. Since I was on High Sierra, I created a new APFS container to install Mojave on before installing it on my main system.

 

[Fishrrman]

Why can't you just use CCC to create a bootable clone of your Sierra install, then boot and run from that cloned backup to run Logic (if you need to)?

That's what a "bootable clone" is all about -- the ability to boot and run from it just as if it were "the original drive". Because, it almost -IS- "the original drive" (it's "a clone", right?).

You didn't say whether you're already a user of CCC.
If not, you can download and try it for FREE for 30 days.
I'd suggest that you make a clone, and try booting and running from it, just to see if it works.
Doing this will "cost you nothing" except the time involved.

Then you'll have "the answer"...

 

[Ebenezum]

OP: Your plan is a good idea. Keep in mind that Mojave converts the drive to APFS and Sierra has only beta level support for it. You might not be able to use the external drive in Sierra after installing Mojave into the external drive. It might not cause any problems but I would recommend taking extra backup to another external drive before installing Mojave just in case. You cant have too many backups...