macOS Sierra: How to do a clean install

A clean install of macOS Sierra could give your Mac better performance and stability. Here’s how to do a clean install of macOS Sierra.


macOS Sierra has finally been released, and Mac users around the world are getting ready to install it on their computers. But the eternal question looms once again: Should you do a clean install or just do an upgrade on your Mac?

My advice is to do a clean install if it’s been a long time since you did one. Over time, as you do one upgrade after another of macOS, you might find that your Mac’s performance slips and that it slows down considerably. A clean install can help fix that and give an older Mac a new lease on life.

I experienced just such a situation a few years ago with a Mac that had gone about five years between clean installs. My iMac was performing horribly and I’d just had enough of the slowness and instability. So I did a clean install of macOS, and wow what a difference! It was almost like getting a new Mac.

Before doing a clean install, make sure you backup all of your data.

How to do a clean install of macOS Sierra

Now that we’ve considered the question of whether or not to do a clean install, here’s how you can do a clean install of macOS Sierra (courtesy of MacRumors):

Download the macOS Sierra installation package from the Mac App Store. Once it has downloaded, follow these steps to create a USB bootable installer.

1. Open Disk Utility (found in the Applications/Utilities folder), select the thumb drive in the sidebar and click the “Erase” button.

2. Name the USB drive “Untitled” if it isn’t already, choose the Format “OS X Extended (Journaled)”, and click “Erase”. Once your thumb drive is formatted and the macOS installation package has finished downloading, open up Terminal (found in Applications/Utilities).

3. Now, ensure the USB drive is the only disk named “Untitled” connected to your Mac, and then paste the following command into the Terminal window, and press Enter: sudo /Applications/Install\ macOS\ “macOS”/Contents/Resources/createinstallmedia –volume /Volumes/Untitled –applicationpath /Applications/Install\ macOS\ “macOS” –nointeraction

4. You should be prompted for your administrator password. Enter it, and the command will create a bootable Sierra installer on the USB drive. The process will take a few minutes to complete, so leave it running.

Once the USB installer has been created, restart your Mac and hold down the Option key as soon as you hear the reboot tone. Then follow these steps:

1. Use the mouse pointer or the arrow keys on your keyboard to select the disk called “Install macOS Sierra” in the drive list that appears on the screen.

2. Once the USB drive has booted, select “Disk Utility” from the Utilities window, choose your Mac’s startup drive from the list, and click “Erase”.

3. When your Mac’s startup disk is formatted, return to the Utilities window and select “Install macOS”, choose your freshly erased startup drive when asked where to install the OS, and follow the onscreen prompts to complete the installation.

More at MacRumors

Once you've gotten a clean install of macOS Sierra done, you can start to enjoy all of the new features listed on Apple's macOS Sierra page. Be sure to also check out this helpful video that covers what's new in macOS Sierra:

I've been running macOS Sierra since the early betas, and I think it's the best version of macOS yet. Enjoy!

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