How Run Two Versions of macOS from External SSD

How To Dual-Boot Mac Run Two Versions of macOS on a Mac. How To Dual Boot macOS Sierra and El Capitan from an External SSD. Run macOS Sierra and El Capitan From an External SSD. Dual Booting macOS Sierra and El Capitan on an External USB 3.0 SSD.

Install and Run macOS Sierra From An External SSD:

How To Create macOS Sierra 10.12.0, 10.12.1 10.12.2 & 10.12.3 USB Boot Disk:

Download macOS Sierra for Free from the Mac App Store when released this fall or if you have a paid Developer License, Download Now from Apple's Developer Website or wait till July to download Public Beta Preview.

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Performed and Tested On MacBook Air (13-inch, Mid 2012) on Samsung V-NAND SSD 850 EVO installed in External USB 3.0 Enclosure and Lexar 32GB USB 2.0 JumpDrive P10. Using OS X El Capitan 10.11.5, macOS Sierra Developer Preview 10.12, macOS Sierra 10.12 & 10.12.1 Official Release.

The Samsung V-NAND 850 EVO SSD was installed in External USB 3.0 Enclosure.

Apple's Intel Based Systems:
Mac Mini
iMac
Mac Pro
MacBook Air
MacBook Pro

TRANSCRIPT:

We've already shown on the previous episode, how to install and run macOS Sierra on an external SSD.

We're now going to create an additional partition on the external SSD, in order to dual boot macOS Sierra and El Capitan.

Soooooo, Let's Get Started.

As usual, since we'll be using Disk Utility, make sure you have or made a backup of your system hard drive or drives before proceeding.

Continuing on, after inserting the SSD in an available USB socket, open Disk Utility.

Now, click on the SSD header in the sidebar, then click the Partition button shown here.

To create an additional partition, click the plus sign button shown here and then name the Partition to whatever you like and make sure that the default format is OS X Extended (Journaled), alternatively, to delete the partition simply click the minus button.

Once satisfied with your choice, click the Apply button to create the new partition.

Now, close Disk Utility and simply launch the macOS El Capitan installer and choose to install on the newly created partition, which, in my case, is named macOS El Capitan SSD.

The remaining installation process, is exactly the same, as was shown in the previous episode.

In summary, after the installation process has finished, El Capitan boots to the Desktop, where, you can optionally set the default startup disk, to that of your Mac system drive after turning on your Mac

Once that's taken care of, anytime you want to run macOS Sierra or El Capitan from the SSD, simply shutdown the Mac and proceed with the power and Option key combination, to boot to the Startup Manager and click the macOS, on the SSD, that you want to boot to.

And that's all there is to it.

Thanks for watching and thumbs-up if you liked this video, and please, don't forget to click that subscribe button, to be notified of the next episode.

Thanks and Peace.

[shasantv]

Having a hard time concentrating on what you are saying because music is too loud.

[sandhewaberyl]

can i have Win10 on my laptop and MacOS on my external drive??

[nathanromano]

I have the new 2016 MacBook Pro and im trying to do this but everytime I run the "El Capitan Installer" I have an error of "The copy you are trying to install is too old for this version of OS X" Please help! Thanks.

[jameslewis]

My macbook pro is running Sierra. I replaced my optical drive with a ssd drive. I want Mountain Lion to run on the ssd drive and keep Sierra on the HD drive. I want to be able to boot up with Sierra or on the ssd drive boot up with Mountain Lion so I can use my music software. How?