Launch Disk Utility and choose the Kingston HyperX flash drive (or whatever other external drive you’re trying to use). That’s not good.įortunately, clicking on it reveals the problem:įind your “Utilities” folder in the “Applications” folder, and identify Disk Utility: The HyperX flashdrive is plugged in so I’ll click on “Show All Disks…” to choose it:īut, hmmm, it’s greyed out, indicating it’s not a selectable option. “BigHD” is my main drive on my MacBook Pro. Given your question, I’m going to assume you’ve already downloaded the disk image (“.dmg”) for the Yosemite installer. And that’s what this article covers.įor this task, I’m using a lovely Kingston 64GB HyperX external USB 3.0 flash drive (about $85 on Amazon). The other problem with using an external drive is making sure that it’s formatted correctly. How many of your USB drives are that big? Of course, you can use an external hard drive too, and the process is similar, so that’s not a complete show-stopper. General rule of thumb for a modern operating system install is to have at least 30GB of space. There are two problems with this strategy, however: First is size. Boot up into Yosemite to play, experiment and test, then go back to the stable, shipping Mavericks for your production work. So yes, installing the OS on an external drive or second partition or similar is very smart. There’s also going to be all sorts of extra system logging for debugging purposes so performance isn’t going to be as snappy as people would prefer and there are issues of upgrading mailbox formats, bookmarks, preferences, etc, just to find out that if you need to back up to 10.9 Mavericks, well, you’re in a big jam.
With a public beta, it’s inevitable that people are going to leap onto the bandwagon so they can have a preview of Mac OS X 10.10 “Yosemite”, just to find that there’s a reason that “beta” is in the name at this point and have things fail to work properly or even at all.