If you've always wanted to partition your Mac's hard drive so you can run a separate operating system — including — in tandem with your current one, it's surprisingly easy to do so thanks to Apple's built-in disk utility program. Here's how to partition your Mac.
Over time the hard drive in your computer will eventually fill up. When transferring your data from one drive to another, we highly recommend you install a fresh copy of the OS. Installing a clean copy of OS X / macOS on your new drive. Mac Help Forums; Hardware & Peripherals. Installing a 2nd hard drive. Thread starter bonzo65; Start date Sep 16, 2005; B. Bonzo65 Registered. Sep 16, 2005 #1. Sep 16, 2005 #1. R - this will be my primary disk but I need to be able to access all my files on the old drive. I need to install a second hard drive in my old G4 tower - this.
What is a disk partition? Partitioning your Mac is basically splitting your hard drive into separate, usable systems. It makes it possible to run two separate operating systems on one device, like Windows and macOS or two versions of macOS (like High Sierra and Mojave). Note: If you want to run Windows on your Mac, Apple's Boot Camp assistant will automatically make a partition for you. It is important to note that partitioning your hard drive also splits up your available hard drive space.
Each partition will take up a portion of your usable storage. So, if you are running low on storage capacity on your hard drive, we don't recommend partitioning; try using an external drive, instead. How to create a partition on your Mac. Open Finder from your dock. Select Applications. Scroll down and open the Utilities folder.
Double-click to open Disk Utility. Select your hard drive in the Disk Utility window. It will be the first drive on the list.
It might be named 'Fusion,' or 'Macintosh HD.' . Click on the Partition tab. Click the plus (+) button. Change the size of the partition you wish to use by dragging the resize controls.
The used space is represented in blue. Name the new partition. Click apply. Disk Utility will check the disk and make changes. This will take several minutes.
How to switch partitions You can switch to the new partition, install the current macOS, and then download and install macOS Mojave from there. Click the Apple icon in the upper-left corner of your screen. Select System Preferences.
From the drop-down menu. Select Startup Disk. Click the Lock in the lower left corner of the window to unlock and make changes. Enter your system admin password. Select your partition drive. Click Restart. You can also restart your Mac and press the Option Key when you hear the startup chime.
This will take you to the Startup Manager and you can select your drive from there. IfYou will then be asked to install macOS. This will install the latest available macOS onto the partitioned hard drive.
You may have to install macOS High Sierra before upgrading to macOS Mojave. If you are testing a beta version of macOS, you'll first install whatever the current version is. Then, you can then install the macOS beta. How to download macOS Mojave If macOS Mojave doesn't automatically install on your partitioned hard drive (if it installs macOS High Sierra instead, for example), you can open the Mac App Store to find and download Mojave from there.
Any questions? Do you have any questions about installing a partition or downloading a new operating system onto a partitioned drive? Let us know in the comments. If you're having trouble partitioning your hard drive, be sure to for help! Updated September 2018: Added information about macOS Mojave.