How to Install Mac OS X Yosemite
If you’re eager to get your hands on OS X Yosemite, Apple has released its upcoming operating system as a free beta for the first million downloaders.
Though Yosemite has been available to registered members of the Mac Developer Program since June, Apple has for the first time in its history decided to give customers a taste of the upcoming software in. The public beta should be stable enough for most regular users, but issues are bound to arise and some third-party programs may not yet work.
To download OS X Yosemite you will need a valid Apple ID, and your Mac should already be running Mavericks 10.9.3. If you’re not familiar with the installation process, be sure to read through this guide for all the steps.
Prepare Your Mac
First off, as with any major software update, be sure to back up to Time Machine, and to a bootable drive using Carbon Copy Cloner or SuperDuper.
There are three ways you can install Yosemite on your Mac: on a separate partition (which Apple suggests), to an external hard drive (not recommended) or by replacing the current Mavericks OS (also not recommended). The following describes how to create a partition on your Mac’s hard drive, so you can test Yosemite without harming your Mac.
Create A Partition
Before you download and install Yosemite, you need to partition your Mac.
1. Launch Disk Utility and select your startup drive, then select Partition. You should have enough free space on your Mac to create at least a 20GB partition for Yosemite.
2. Click the plus “+” button at the bottom of the partition layout to create another partition. Select it input the amount space you want (Apple recommends 8GB minimum, but you’ll need 20GB to test it properly). Under Format, select the Mac OS Extended (Journal) from the drop-down list. Name your partition “Yosemite Test” or similar so you know which one to delete when the time comes.
3. Click Apply to start the partition process. Make sure the pop-up dialogue box says that no partitions will be erased, especially your main startup drive.
Download & Install The Beta Installer
To download Yosemite, you will need to join the OS X Beta Program using your Apple ID. After signing in and reading over the guide, scroll to the bottom of the page and click the blue redemption code button. Once you’ve confirmed and read the information, the Mac App Store will launch then you can sign in and begin downloading the Yosemite Installer application, which is a little over 5GB.
The Yosemite Installer is downloaded to your Applications folder. When installer opens up, select the Yosemite partition you created, and click the install button. If you want to try Yosemite on other Macs, make sure you take a copy of the installer before you run it.
To install the beta, simply run the installer you just downloaded. When prompted, carefully select the partition you created earlier, as per the screenshot above. Follow the prompts, until eventually your Mac restarts to complete the installation.
Don’t Use iCloud Drive
After the installer restarts your Mac and installs Yosemite, you will be presented with a series of questions similar to the ones you got when installing Mavericks.
You should avoid upgrading to iCloud Drive if you rely on devices using older versions of OS X or iOS, due to incompatibilities between the new iCloud Drive and older software. You can enable iCloud Drive under System Preferences > iCloud after the official release.
To get back to Mavericks while in Yosemite, launch System Preferences > Startup Disk. Select your main drive and click restart. You can also hold down the option (alt) key at startup and choose your partition from there.
When it comes to installing Yosemite proper, upgrade from within your Mavericks installation and then you can use Disk Utility to delete the test partition you created for the beta.