Yes, you clarified it. I don't completely understand the lingo and the complicated steps but I do get most of it. So, this may be way off base as Artie would say, but does this mean that the external drive I have for my old MBP cannot be used to boot up my new MBP even though it won't have Sierra on it?

After I get this all settled, I want to have an external drive backup for both of my MBP's. I just don't know if I can use the same one for both machines. It is a terabyte though. I'll never use all that space, at least for now.


Originally Posted By: joemikeb
Originally Posted By: Plantsower
I am not sure what you mean by or a Recovery Drive image.

This is a long answer to a short question, but some background is necessary for this to make sense.

There are utilities, such as TechTool Pro's ProToGo that can create bootable subsets of MacOS so you can run TechTool Pro or other troubleshooting and/or repair utilities from say a thumb drive. As you can imagine this can be a useful troubleshooting tool. The gotcha in this is the bootable subset is created from a particular machine and because the MacOS installer installs a system that is unique to a particular Mac model those ProToGo subsets will only work with Mac of the same model it was created on. For example a ProToGo drive created on my late 2012 Mac Mini will only boot a late 2012 Mac Mini and maybe not even every late 2012 Mac Mini because mine has been relatively heavily modified over the years.

The only bootable image (a.k.a. volume or drive) that will boot every Mac compatible with the particular release of MacOS is the "Recovery Drive". The use of the term image refers to the fact it is like a photograph or other "image" that is the same everywhere it occurs.

One of the ProToGo options is a Recovery Drive.

Did I clarify or obscure?

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