How to Install OS X Yosemite Beta on a New Partition & Safely Dual Boot
OS X Yosemite is an amazing update to the Mac operating system that’s really better experienced than seen, but due to it’s current early beta status, it’s generally not a good idea to upgrade your primary OS X volume to the 10.10 beta quite yet. Instead, the safest approach is to install OS X Yosemite onto a separate partition of the hard drive, keeping it separate from your primary stable and productive existing OS X experience.
This allows you to check out OS X Yosemite and dual boot between the OS X 10.10 beta and OS X 10.9 (or 10.8) without each operating system impacting one another, and you can safely switch between the two with a simple reboot process. This also allows you to uninstall Yosemite at any point easily if you want to.
This guide is intended for those with access to the OS X Yosemite beta, typically through a developer account.
Prerequisites Before Beginning
- Download OS X Yosemite – At the moment, you will need a Mac developer account to do this, anyone can apply for a dev account and pay the fee if desired, this allows you to download the OS X Yosemite Dev Preview installer through the Mac App Store
- Check system requirements to be sure that the Mac can run OS X Yosemite, generally if the Mac will run Mavericks, it will run Yosemite
- At least 25GB of disk space available to create a separate partition and install Yosemite onto
- Back up your Mac – you’re going to be modifying the partition table of the hard disk and installing beta software. Always back up everything before doing either, the simplest way to do this for most Mac users is simply to use Time Machine and initiate a backup manually.
Once downloaded and having the Mac backed up, do not proceed with the Yosemite installation quite yet, you need to create the partition first if you want to keep the two operating systems separate and dual boot.
Create an OS X Yosemite Partition
The first thing you’ll do is partition the hard drive of the Mac to create a new partition for OS X 10.10 Yosemite to install on. This insures that your primary Mac OS X installation remains separate and preserved while testing Yosemite:
- Open the Disk Utility app, found in /Applications/Utilities/ and choose your hard drive from the left menu
- Choose the “Partition” tab, then click on the [+] plus button to create new partition
- Label the new partition something obvious, like “OS X Yosemite”, and then assign the partition a reasonable amount of space, a minimum of 15GB should be required but allocating more space is better if you plan to use Yosemite often (25GB+)
- Choose “Apply” to modify the partition table to create the new partition
Exit out of Disk Utility when finished, you’re good to start the installation now onto that fresh partition.
Install OS X Yosemite to the New Partition
With the whole system backup complete, Yosemite downloaded, and the partition made, you can now safely install OS X 10.10 onto the separate partition, this will allow you to preserve your existing OS X installation without mucking it up with beta software.
- Return to the OS X Yosemite installer and launch it (look in the /Applications/ folder for “Install OS X 10.10 Developer Preview”
- Select “OS X Yosemite” (or whatever you named the partition) as the installation destination
- Let the installation complete, the Mac will automatically boot into OS X Yosemite when complete
Enjoy OS X Yosemite! Remember, it’s in beta right now, so some things are fairly buggy and not every feature is fully implemented quite yet. Things will continue to evolve with each new release and update though, and you’ll be able to install those updates through the Mac App Store when they become available.
Dual Booting: Switching Between OS X 10.10 and OS X 10.9
Now that the installation is complete, you can dual boot between OS X Yosemite and OS X Mavericks (or whatever OS X you’re running). The easiest way to do this is by holding down the OPTION key during boot and selecting the partition volume according to the version of OS X you want to boot. Assuming you labeled OS X Yosemite partition descriptively enough, it’ll be easy to pick out.