How to make a bootable Sierra installer drive in case you want to downgrade from macOS High SierramacOS High Sierra is the new hotness, but what if you want to keep a copy of macOS Sierra, too?
If you are planning to upgrade to macOS High Sierra, there is one additional set of steps you should follow. You should download a bootable copy of macOS Sierra. This allows you to use it if you partition your hard drive for dual-software installation. It is also the only way to downgrade to the older format if you decide you don't like macOS High Sierra at all.
Before you start
How to format your external drive for Mac
How to make your external drive bootable for Sierra
How to use Sierra with a bootable drive
Before you start
Before you get started, make sure you have a thumb drive with at least 8GB of storage, or a spare external hard drive (one that you don't use with anything else).
You'll also need to download macOS Sierra from the Mac App Store.
Note: After macOS Sierra has downloaded, it will automatically begin the installation process. Close the installer instead.
Please,...
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How to make a bootable Sierra installer drive in case you want to downgrade from macOS High Sierra
