DIY: How to Format a Mac and Clean Install Mountain Lion (OSX 10.8.3)

This posting is a little off-topic from the usual postings here at By the Way the Crow Flies, but I felt that it was of the highest importance to repost the information within.

Over 60% of those viewing this blog are doing so from a Mac (according to blogspot.com statistics).  I created this blog from a Mac and do the majority of my updates from a Mac or an iOS device (iPad or iPhone). Occasionally, I do use my Windows PC (desktop) to post or edit things on the blog, but it is very rarely that I do this.  I could not picture life without a Windows PC, but I could not picture life without a Mac either. Both are equally important and offer their own benefits and uses.  If I had my way, I would only own Mac's for all my computers.  My MacBook Pro has both OS X Mountain Lion and Windows Vista Business Edition installed on it.  This not only creates the ultimate computer but allows me to utilize any/all software currently available for computer users.

This is not a posting arguing which platform is better or what the benefits are of either, it is exactly what the title suggests. I am only stating the info to help readers understand why I am posting this information.  On Windows machines, a nice format and clean install is necessary for optimal performance at least once a year, but should be done to rid the machine of stray files and dead end code as often as 4 times a year. This is just the nature of the beast....Windows.  However, OS X (the Apple OS), is written and performs entirely different than Windows.  I have now owned a Mac for 3.5 years and can say that in that time I have only done a complete format and clean install once!  I am preparing today to do this for a second time as I have some application extensions causing glitches in the OS and conflicting with the NVidia Graphics Driver.  The computer gets caught in these loops where it just keeps restarting at random intervals, sometimes the intervals are so close, the Mac just starts up and before I can type my credentials into the login screen, I'm watching the boot process start from the beginning again. Because Apple OS's are so different from Windows, the process of performing a Format and Clean Install is much different. It does involve a few extra steps, but nothing difficult if you follow the directions contained here.

Last time I performed the format and install was before Mountain Lion (ML) had been released and I was running Lion.  To do so required me to format, install Snow Leopard, then Lion, then load my saved backup. This was a complicated and lengthy process. While doing some Googling, I discovered a Chinaman who had figured out a fairly simple process for doing the format and clean install with Mountain Lion. The Chinaman's process is so good that he even took the time to type up a step by step article with screen shots for you to follow along.  I am posting for the last time on my Mac, before I begin the format and clean install. Next time I post here, I will have a fresh copy of ML installed with all updates and (hopefully) no glitches!

How To Clean Install Mac OS X Mountain Lion

By Hongkiat.com

In the Windows’ analogy, this is like reformatting your Macbook or iMac and reinstalling a brand new version of Mac OS X Mountain Lion. Unfortunately in Mac the process can be a little more complicated and less well known. But first, why should you clean install the Mac OS X Mountain Lion at all?

Here are couple of reasons we can think of: One, your existing Mac OS X inherited documents, files and applications that take up a lot of unnecessary storage space. To optimize your Mac, it is quite necessary to reinstall and start from a clean slate.

Two, you are thinking about trading or gifting your machine to someone else, but you are concerned with the remnants of files, profiles and various credentials that if mishandled, may lead to a security leak. A clean install will give you peace of mind.

With that cleared up, in this article we will show you how to erase existing data and reinstall a brand new copy of Mountain Lion. Here is a breakdown of the steps involved:

1. Download a copy of Mac OS X Mountain Lion
2. Make a bootable drive of Mac OS X Mountain Lion with a USB drive
3. Reboot, Clean up and Reinstall

You ready? Let’s do it.

Recommended Reading: Mountain Lion: 18 Subtle and Hidden New Features

1. Re-Download Mountain Lion

First, grab hold of a copy of the Mountain Lion installer file. The installer you downloaded fro the AppStore automatically deletes itself after you’ve successfully upgraded your Mac.

Here’s how you can download and obtain a soft copy of Mountain Lion.

Launch App Store, and go to the Purchases tab.

Look for OS X Mountain Lion, hold down the Option key and click Download.

Re-enter your App Store credentials if required. If you’ve previously purchased a copy of Mountain Lion, don’t worry, you will not be recharged. Note that this may take up between 10 and 60 minutes, depending on your Internet connection speeds.

While you wait, get a coffee, a break and a USB drive with at least 8 GB capacity. Make sure that you won’t need any of the contents of the flash drive, if you do, keep a backup of it somewhere first.

When you get back, we will look at how you can create a bootable copy of OS X Mountain Lion on your USB drive.

2. Create Bootable OS X Mountain Lion

Do not start the installation process when your download finishes. Our goal is here to keep a soft copy of the installer and in the flash drive.

Once your download is done, go to Finder > Applications. Look for the file called "Install OS X Mountain Lion", right-click and select Show Package Contents.

Navigate to Contents > SharedSupport, then look for the filename "InstallESD.dmg"

Double-click InstallESD.dmg to open/mount it on your Desktop. This may take a minute or two.

Plug in the flash drive into your Mac and launch the Disk Utility application. You can do it quickly by searching via Spotlight.

In Disk Utility, do the following 4 steps carefully:

1. Select the USB drive on the left menu,
2. Select the Erase tab,
3. Select Mac OS Extended (Journaled) for the format.
4. Click the Erase button.

Note: This will remove everything in the flash drive. Keep a backup of the files within if you still need them, then come back to this section.

Once the flash drive is formatted, re-select the formatted USB drive from the left menu, and click theRestore tab.

Next, we are going to create a bootable OS X Mountain Lion in the flash drive. Do the following steps carefully:

1. Drag the formatted drive from the left menu to the Destination field.
2. Drag "Mac OS X Install ESD" on the left menu to Source.
3. Click the Restore button. Installation may take about 10 – 20 minutes.

Once it’s done you’ll have yourself a flash drive with a bootable Mountain Lion.

3. Reboot, Clean Up And Reinstall

So we’ve downloaded a new copy of Mountain Lion and made it bootable in a flash drive. Next up, we’ll attempt to remove everything from the current OS and reinstall a new copy of Mountain Lion.

First, a reboot! Hold down the Option key as you restart and you’ll end up at the screen below. Then, select the Mac OS X on the right.

You’ll be taken to the OS X Utilities dialogue. Select Disk Utility.

At the Disk Utility screen, make sure you have these selected:

• You are selecting your Mac’s hard disk drive (and not your flash drive’s) on the left menu.
• You are on the Erase tab.
• You have selected the "Mac OS Extended (Journaled)" format.

Click the Erase button button and everything (including files, applications, settings, etc) in your Mac will be completely deleted.

Note: Do this with caution as there will be no way for recovery from this point onwards.

(3.4) When you are done, you’ll be directed back to the OS X Utilities dialogue. This time, selectReinstall OS X, the second option from the list.

That’s It!

Your Mac will now reinstall from the flash drive and you’ll end up with a clean piece of Mac OS X Mountain Lion OS, as if your MacBook or iMac was brand new.

Please leave comments letting me and others know if this process worked for you. If you have any questions they can be posted as comments so that all who view the blog can assist you and provide feedback. I check the comments section daily and will answer any questions you may have as well. Happy Macing!