How to install OS X 10.10 Yosemite on an SD card to avoid messing up your Mavericks setup.
Ok, so here we go…
2. Partition your SD card. This allows you to have your brand new OS X install on one partition while also being able to use another partition for other file transfers and storage. Trying to have your files and new OS on the same partition will ruin the OS install.
So partition it with at least 20GB for your OS X install. Being that it’s a beta, you’re not going to be storing many files on there, primarily because the OS is not yet compatible with much of anything, and also because so much can go wrong with a beta that you’d be practically asking to loose your files.
Partition with Disk Utility, in the Partion tab (your SD card shouldn’t have anything on it at this point, cause it’s about to get erased) choose Format “Mac OS Extended (Journaled)” and a name for each partition. I have 3 partitions on my 128GB card, 2 for operating systems (OS X Yosemite and Windows), and my 3rd partition for file transfers.
3. Download the OS X beta – imzdl.com – and launch the package. When prompted where to install the new OS X, CHOOSE THE SD CARD! !Important!
If you don’t choose your SD card as the installation disk, you could easily overwrite your primary OS X, and life as you know it will come to a halt.
The installation will restart the machine and the rest happens by itself. Once it installs it will walk you through initial setup options like choosing a language, wifi network, etc.
One note is that it’s important the SD card doesn’t get interrupted while the new beta OS X is running. Some people are even buying shortened SD cards so that they don’t stick out of the machine as much.
Hope you enjoy experimenting with the new OS X beta!