“If you do decide to participate in the Yosemite beta program, I recommend creating a bootable installer drive, on an external hard drive or a thumb drive (USB stick), for many of the same reasons I recommend making a bootable Mavericks installer drive: If you want to install the Yosemite beta on multiple Macs, using a bootable installer drive can be more convenient than downloading or copying the entire installer to each computer,” Dan Frakes writes for Macworld.
“If you need to erase the drive on your test Mac before installing Yosemite, or start over at any time, you can use a dedicated installer drive to boot that Mac, erase its drive, and then install the OS,” Frakes writes. “And if your beta-testing Mac is experiencing problems, a bootable installer drive makes a handy emergency disk.”
Frakes writes, “As with previous versions of OS X, it’s not difficult to create a bootable installer drive from the Yosemite beta installer, though the processes have changed slightly since Mavericks. ”
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