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rrazmataz Author

Level 1

13 points

I would like to do a clean install of OS Mojave but keep OS High Sierra on an external drive.

I have a 2012 MB Pro with an 500GB internal SSD, 16GB of Ram and a Time Machine as well a Carbon Copy Cloner back ups on two seperate ext. drives. Here is my question. I have a spare blank ext. drive that I would like to mirror my current internal drive if that is possible. Then I would like to do a clean install of Mojave on my internal drive but be able to plug in my external with High Sierra in case there are hiccups or I need to retrieve a program or information that was lost due to the clean install. Is this possible and if so, what is the best way to do it.

MacBook Pro

Posted on Aug 17, 2019 8:29 AM

Top-ranking reply

macjack

Level 10

111,204 points

Posted on Aug 17, 2019 8:45 AM

Sure, you can. Just boot into Startup Manager and choose it.

How to select a different startup disk - Apple Support

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I would like to do a clean install of OS Mojave but keep OS High Sierra on an external drive.

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