Clean Install of OS X Yosemite from Flash Drive

I know I wrote another article earlier about installing OS X from CD. Well, it came time to fix a screw-up I made. I’m not sure exactly what happened, but while messing around with Parallels desktop I activated bootcamp and I couldn’t activate filevault to have an encrypted disk. NOT a good thing for me, since it’s a laptop and if this thing walks away (LIKE MY LAST ONE) then the information won’t be protected.

So, the first thing I did was made sure I had OS X Yosemite downloaded from the App Store. It saves to the Application folder, by default.  Also, now is a good time to toss on an external disk and make a time machine backup of your system.  I use a 1TB external portable disk drive.  If you’re looking to start fresh, don’t worry about it then.
You’ll need a USB flash drive to hold the installation software with at least 8GB space. Mine was 32GB, which is more than 8GB, so I was okay.

How to Create Bootable USB Flash Drive

First, create bootable USB flash drive. Here is how you do it, courtesy of Redmond Pie:

Plug in your USB drive into the computer and open Disk Utility (in Applications).
Select the USB drive from the left sidebar and click on Erase tab.
Choose Mac OS Extended (Journaled) in the format box and let the name be Untitled (default).
Now click on Erase button and wait until the format process completes.
Then choose Partition tab and select 1 Partition from Partition Layout dropdown menu. Click on Option and ensure GUID Partition Table is selected as the partition scheme, with its name set to Untitled.
After downloading the OS X 10.10 Yosemite installer from the Mac App Store, just quit the installer and set the downloaded file’s name to Install OS X Yosemite.app.
Launch the Terminal app (in Applications/Utilities) and type or paste the following command in, and then hit Enter:
sudo “/Applications/Install OS X Yosemite.app/Contents/Resources/createinstallmedia” –volume /Volumes/Untitled –applicationpath “/Applications/Install OS X Yosemite.app” –nointeraction
Note: The code above has missing double dashes in the quotes. Please replace a single “-” with “- -” when you enter the above command line in the terminal.

This will create the bootable USB flash drive. This takes between 10-20 minutes. Do not interrupt the Terminal or eject the flash drive during the process. Once the process completes, you will see the message “Copy Complete. Done.”
The OS X Yosemite bootable USB flash drive will be ready for use and you can start the clean installation process.

After that’s done, keep the USB flash drive in and reboot.  When the start-up sound comes, hold down the “option” key.  After  a while, the partitions available will appear and you can choose it then hit <enter>.

Once the installer pops up, select disk utility and continue.
Click on the Macintosh HD on the left hand pane and click erase tab on the upper right of the window.  click the erase button at the bottom right.  This is going to wipe your startup disk.

Once it’s done, go to the first screen and select Install OS X, then continue.

Select the partition you just erased, then Install.

If everything was done right, the system will install the operating system.  You will be prompted along the way for the time machine disk to complete the configuration.  This is what I did, and it’s easy to select what you want to have migrated into the new operating system.

Of course, afterwards it’s time to make your new OS your very own and customize as you wish 🙂

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