Hey there guys,
I hope that this post finds you all in excellent spirits, and that you are having a great weekend.

We use DVD Studio Pro to create DVDs from material edited in FCP X and exported via Compressor. We run DVD Studio Pro ('DVDSP') on one MacBook Pro (15” Retina, mid-2012) and house FCP X and Compressor on another one (15” Retina, 2016).

The 2012 MacBook Pro with DVDSP on it is running OS X 10.8.5. We have kept it this way for reasons of compatibility. However, a couple of other apps that are very important to us no longer support this operating system, and have stopped working. We are therefore thinking of updating the OS on this machine.

So my two-part question is as follows:

1. What is the latest version of OS X or macOS that DVD Studio Pro successfully runs on?

2. Is it possible to install the latest version of macOS on a separate external hard drive, and boot this OS on the 2012 MacBook Pro, while leaving the original OS on Macintosh HD intact - effectively, switching between the two where necessary?

Any guidance, tips, ideas etc. are sincerely appreciated.

Thank you very much indeed for reading this!

You can indeed install a current version of macOS on a secondary drive, and leave the internal drive on the legacy version of OS X. When you boot, you'll hold the Option key when restarting, then select which drive to boot from.
support.apple.com/en-us/HT202796

FCPX.guru wrote:
Thank you so much for your kind and informative reply!

Can the external HD contain anything else aside from Mac OS X/macOS? For example, does it have its own 'Macintosh HD' to which you can save documents, etc?

Machintosh HD is the default name given to your internal hard drive. The external bootable drive would be simply another "Macintosh HD" drive. They're both just system drives. So, "yes".

It might be easiest to keep the apps that require the older OS installed into the Applications folder of the drive that the old OS is on (in your case, the external drive). It's not necessary but basically booting from the external drive will show you a different desktop than the internal drive. So they are both their own self-contained systems and have all the capabilities it would if it was internal. Just be sure to get an external drive with sufficient speed and space. Also make sure your computer can run the older OS. I think some Macs have a limit on how far back they can go.

FCPX.guru wrote:
Brilliant! So I guess that I can use Time Machine to back up the system on the 10.8.5 computer, install the latest macOS on the external drive and then just transfer the data across to the new external HD.

Redifer wrote:
Thank you very much indeed for your kind and detailed response! We will probably end up installing the new macOS iteration on an external SSD drive, and booting from there.