Along with its announcement of the next version of OS X, Apple has made OS X 10.10 “Yosemite” available to the public as part of its beta test program, which it recently opened up to include more than its developer community and a select group of testers.
Keep in mind that being a beta program, the OS will have a number of bugs and incomplete features, which may result in data loss, system instability, and other frustrations. This is especially true if you use third-party system monitoring and security software, some popular examples of which are anti-malware tools, and firewall software like Little Snitch.
While Apple prefers you install the beta on a system that you regularly use, if you use the OS X installation on your main Mac, then you might encounter an error that requires you restore your system from backup, or otherwise have to go in depth to fix the issue at hand.
This may be particularly pertinent as the beta testing goes on, and new builds are released that may introduce more bugs as others are fixed.
Instead of using your main Mac as a test bed for OS X Yosemite, consider some alternatives that will give you a look at the new OS, which include installing on a secondary hard drive, a secondary partition, in a virtual machine, or on another Mac altogether. To do this, when you sign up for the public beta you will get a purchase code for the App Store, and instructions for downloading the beta. Follow these instructions and a 5GB installation application will be placed in your Applications folder, and be run automatically.
Before proceeding with any installation, go to the Applications folder and locate the program called “Install OS X 10.10 Developer Preview” and copy it to another location, such as your Downloads folder or the Desktop. This will prevent it from being automatically deleted after being run, so you can access it later without re-downloading it.
After copying the installer, be sure to attach a backup drive and then use Time Machine or a cloning tool to make a full and restorable backup of your system.
Install on a secondary hard drive
Get an external hard drive that is connected directly to your Mac via USB, Firewire, or Thunderbolt, and then use Disk Utility to format it with a GUID partition scheme, and Mac OS Extended (Journaled) as the format type. When done, go back to the Yosemite installer and proceed with the on-screen instructions until you see the disk chooser for where to install the OS. You should see the external drive as an option, which you can then select and continue the installation.
Install on a secondary partition
If you have a secondary drive in your Mac, or a secondary partition already available, then you can use this for installing the new beta. Alternatively, you can create a partition dedicated to testing:
- Open Disk Utility and choose your hard drive device (above the name of the boot volume in the side bar)
- Click the Partition tab that appears when you do this.
- Select the graphical partition graph and click the plus button underneath it to create a new partition.
- Drag the dividing bar between the partitions to specify the size of the new partition (at least 10GB), followed by giving it a name and using “Mac OS Extended (Journaled)” as the format.
- Click Apply to create the new partition.
With the partition made, you can go back to the OS X installer, and as with a secondary hard drive, you can proceed with the installer’s instructions and select the new partition when prompted for where to install OS X Yosemite.
Install in a Virtual Machine
Virtual Machine software may be a great way to try out OS X Yosemite, since it allows you to run the OS in an isolated environment within your main Mac, without needing to restart your system. The easiest way to do this is to launch a current VM installation of OS X Mavericks, and then copy the Yosemite installer to it. From here you can run the installer to upgrade the VM to Yosemite. Alternatively you can simply download the installer from the Mac App Store within the VM.
Do keep in mind that your VM software may need to be updated first before it can run Yosemite, especially if you are using older VM software. If you cannot install Yosemite on your VM, then check with your VM’s developer to see when support for Yosemite will be available.
While VM software can be convenient, it does present a custom environment for running OS X, which may not behave exactly how OS X will run on native Apple hardware. Therefore, be aware that this might result in odd behavior at first, which will need to be addressed by the developers of your VM software. Keep in mind that with this installation being an unsupported beta, you may not get any solutions to problems you are experiencing, and might have to wait a while for any patches to become available.
Install on another Mac
The final option for safely testing the new OS X Beta is to simply use another Mac. If you have an older Mac around, then consider copying the installer to it, and running it on the system. Apple has not made any changes to the requirements for Yosemite from Mavericks, so if you have a Mac that will support Mavericks, then you can install Yosemite on it.