If you want to install a version of macOS that you never downloaded from the App Store, then you’ll need to enlist the help of another Mac user. In the best case scenario, you’ll want to dual boot a version of macOS that you previously downloaded, as this means you’ll be able to re-download the installer from the App Store. If this is a newer version of macOS, then you can download the installer as normal, but if it’s an earlier version of macOS then things become slightly more complicated. Next, you need to download the installer for the version of macOS that you want to install. Once you’re happy with the information you’ve entered, select “OK” followed by “Add.”.You can also set a “Quota Size” which is the maximum amount of storage this volume can allocate. If you want to manually manage the APFS volume allocation, then select “Size options” and enter a “Reserve Size,” which is the amount of storage that will always be available for this volume.Alternatively, you can use APFS (Encrypted), APFS (Case-sensitive), or APFS (Case-sensitive, Encrypted). If you’re using macOS 10.13 or later, then APFS is the recommended format. Open the “Format” pop-up menu, and then choose a format.In Disk Utility’s left-and menu, select an existing APFS volume, and then select the “Volume: Add” button.In the Disk Utility toolbar, select “View > Show All Devices.”.Open the “Finder” and navigate to “Applications > Utilities.”.The first step, is to create a new volume:

With the release of High Sierra and Mojave, dual booting has just become a lot easier! These versions of macOS support Space Sharing, which is a feature of the Apple File System (APFS) where the available space is shared between different volumes, so you can install a second version of macOS with no reformatting required. Before making any system-level changes, you must always make a full Time Machine backup, just so you have something to restore in the unlikely event that everything goes horribly wrong.

How to install high sierra on mac